--- /dev/null
+//===- InstructionCombining.cpp - Combine multiple instructions -----------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// InstructionCombining - Combine instructions to form fewer, simple
+// instructions. This pass does not modify the CFG. This pass is where
+// algebraic simplification happens.
+//
+// This pass combines things like:
+// %Y = add i32 %X, 1
+// %Z = add i32 %Y, 1
+// into:
+// %Z = add i32 %X, 2
+//
+// This is a simple worklist driven algorithm.
+//
+// This pass guarantees that the following canonicalizations are performed on
+// the program:
+// 1. If a binary operator has a constant operand, it is moved to the RHS
+// 2. Bitwise operators with constant operands are always grouped so that
+// shifts are performed first, then or's, then and's, then xor's.
+// 3. Compare instructions are converted from <,>,<=,>= to ==,!= if possible
+// 4. All cmp instructions on boolean values are replaced with logical ops
+// 5. add X, X is represented as (X*2) => (X << 1)
+// 6. Multiplies with a power-of-two constant argument are transformed into
+// shifts.
+// ... etc.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "instcombine"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Pass.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/GlobalVariable.h"
+#include "llvm/Operator.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Support/ConstantRange.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Support/InstVisitor.h"
+#include "llvm/Support/IRBuilder.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/PatternMatch.h"
+#include "llvm/Support/TargetFolder.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
+#include <algorithm>
+#include <climits>
+using namespace llvm;
+using namespace llvm::PatternMatch;
+
+STATISTIC(NumCombined , "Number of insts combined");
+STATISTIC(NumConstProp, "Number of constant folds");
+STATISTIC(NumDeadInst , "Number of dead inst eliminated");
+STATISTIC(NumDeadStore, "Number of dead stores eliminated");
+STATISTIC(NumSunkInst , "Number of instructions sunk");
+
+/// SelectPatternFlavor - We can match a variety of different patterns for
+/// select operations.
+enum SelectPatternFlavor {
+ SPF_UNKNOWN = 0,
+ SPF_SMIN, SPF_UMIN,
+ SPF_SMAX, SPF_UMAX
+ //SPF_ABS - TODO.
+};
+
+namespace {
+ /// InstCombineWorklist - This is the worklist management logic for
+ /// InstCombine.
+ class InstCombineWorklist {
+ SmallVector<Instruction*, 256> Worklist;
+ DenseMap<Instruction*, unsigned> WorklistMap;
+
+ void operator=(const InstCombineWorklist&RHS); // DO NOT IMPLEMENT
+ InstCombineWorklist(const InstCombineWorklist&); // DO NOT IMPLEMENT
+ public:
+ InstCombineWorklist() {}
+
+ bool isEmpty() const { return Worklist.empty(); }
+
+ /// Add - Add the specified instruction to the worklist if it isn't already
+ /// in it.
+ void Add(Instruction *I) {
+ if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second) {
+ DEBUG(errs() << "IC: ADD: " << *I << '\n');
+ Worklist.push_back(I);
+ }
+ }
+
+ void AddValue(Value *V) {
+ if (Instruction *I = dyn_cast<Instruction>(V))
+ Add(I);
+ }
+
+ /// AddInitialGroup - Add the specified batch of stuff in reverse order.
+ /// which should only be done when the worklist is empty and when the group
+ /// has no duplicates.
+ void AddInitialGroup(Instruction *const *List, unsigned NumEntries) {
+ assert(Worklist.empty() && "Worklist must be empty to add initial group");
+ Worklist.reserve(NumEntries+16);
+ DEBUG(errs() << "IC: ADDING: " << NumEntries << " instrs to worklist\n");
+ for (; NumEntries; --NumEntries) {
+ Instruction *I = List[NumEntries-1];
+ WorklistMap.insert(std::make_pair(I, Worklist.size()));
+ Worklist.push_back(I);
+ }
+ }
+
+ // Remove - remove I from the worklist if it exists.
+ void Remove(Instruction *I) {
+ DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
+ if (It == WorklistMap.end()) return; // Not in worklist.
+
+ // Don't bother moving everything down, just null out the slot.
+ Worklist[It->second] = 0;
+
+ WorklistMap.erase(It);
+ }
+
+ Instruction *RemoveOne() {
+ Instruction *I = Worklist.back();
+ Worklist.pop_back();
+ WorklistMap.erase(I);
+ return I;
+ }
+
+ /// AddUsersToWorkList - When an instruction is simplified, add all users of
+ /// the instruction to the work lists because they might get more simplified
+ /// now.
+ ///
+ void AddUsersToWorkList(Instruction &I) {
+ for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
+ UI != UE; ++UI)
+ Add(cast<Instruction>(*UI));
+ }
+
+
+ /// Zap - check that the worklist is empty and nuke the backing store for
+ /// the map if it is large.
+ void Zap() {
+ assert(WorklistMap.empty() && "Worklist empty, but map not?");
+
+ // Do an explicit clear, this shrinks the map if needed.
+ WorklistMap.clear();
+ }
+ };
+} // end anonymous namespace.
+
+
+namespace {
+ /// InstCombineIRInserter - This is an IRBuilder insertion helper that works
+ /// just like the normal insertion helper, but also adds any new instructions
+ /// to the instcombine worklist.
+ class InstCombineIRInserter : public IRBuilderDefaultInserter<true> {
+ InstCombineWorklist &Worklist;
+ public:
+ InstCombineIRInserter(InstCombineWorklist &WL) : Worklist(WL) {}
+
+ void InsertHelper(Instruction *I, const Twine &Name,
+ BasicBlock *BB, BasicBlock::iterator InsertPt) const {
+ IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt);
+ Worklist.Add(I);
+ }
+ };
+} // end anonymous namespace
+
+
+namespace {
+ class InstCombiner : public FunctionPass,
+ public InstVisitor<InstCombiner, Instruction*> {
+ TargetData *TD;
+ bool MustPreserveLCSSA;
+ bool MadeIRChange;
+ public:
+ /// Worklist - All of the instructions that need to be simplified.
+ InstCombineWorklist Worklist;
+
+ /// Builder - This is an IRBuilder that automatically inserts new
+ /// instructions into the worklist when they are created.
+ typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy;
+ BuilderTy *Builder;
+
+ static char ID; // Pass identification, replacement for typeid
+ InstCombiner() : FunctionPass(&ID), TD(0), Builder(0) {}
+
+ LLVMContext *Context;
+ LLVMContext *getContext() const { return Context; }
+
+ public:
+ virtual bool runOnFunction(Function &F);
+
+ bool DoOneIteration(Function &F, unsigned ItNum);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addPreservedID(LCSSAID);
+ AU.setPreservesCFG();
+ }
+
+ TargetData *getTargetData() const { return TD; }
+
+ // Visitation implementation - Implement instruction combining for different
+ // instruction types. The semantics are as follows:
+ // Return Value:
+ // null - No change was made
+ // I - Change was made, I is still valid, I may be dead though
+ // otherwise - Change was made, replace I with returned instruction
+ //
+ Instruction *visitAdd(BinaryOperator &I);
+ Instruction *visitFAdd(BinaryOperator &I);
+ Value *OptimizePointerDifference(Value *LHS, Value *RHS, const Type *Ty);
+ Instruction *visitSub(BinaryOperator &I);
+ Instruction *visitFSub(BinaryOperator &I);
+ Instruction *visitMul(BinaryOperator &I);
+ Instruction *visitFMul(BinaryOperator &I);
+ Instruction *visitURem(BinaryOperator &I);
+ Instruction *visitSRem(BinaryOperator &I);
+ Instruction *visitFRem(BinaryOperator &I);
+ bool SimplifyDivRemOfSelect(BinaryOperator &I);
+ Instruction *commonRemTransforms(BinaryOperator &I);
+ Instruction *commonIRemTransforms(BinaryOperator &I);
+ Instruction *commonDivTransforms(BinaryOperator &I);
+ Instruction *commonIDivTransforms(BinaryOperator &I);
+ Instruction *visitUDiv(BinaryOperator &I);
+ Instruction *visitSDiv(BinaryOperator &I);
+ Instruction *visitFDiv(BinaryOperator &I);
+ Instruction *FoldAndOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
+ Instruction *FoldAndOfFCmps(Instruction &I, FCmpInst *LHS, FCmpInst *RHS);
+ Instruction *visitAnd(BinaryOperator &I);
+ Instruction *FoldOrOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
+ Instruction *FoldOrOfFCmps(Instruction &I, FCmpInst *LHS, FCmpInst *RHS);
+ Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op,
+ Value *A, Value *B, Value *C);
+ Instruction *visitOr (BinaryOperator &I);
+ Instruction *visitXor(BinaryOperator &I);
+ Instruction *visitShl(BinaryOperator &I);
+ Instruction *visitAShr(BinaryOperator &I);
+ Instruction *visitLShr(BinaryOperator &I);
+ Instruction *commonShiftTransforms(BinaryOperator &I);
+ Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI,
+ Constant *RHSC);
+ Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
+ GlobalVariable *GV, CmpInst &ICI,
+ ConstantInt *AndCst = 0);
+ Instruction *visitFCmpInst(FCmpInst &I);
+ Instruction *visitICmpInst(ICmpInst &I);
+ Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
+ Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
+ Instruction *LHS,
+ ConstantInt *RHS);
+ Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
+ ConstantInt *DivRHS);
+ Instruction *FoldICmpAddOpCst(ICmpInst &ICI, Value *X, ConstantInt *CI,
+ ICmpInst::Predicate Pred, Value *TheAdd);
+ Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
+ ICmpInst::Predicate Cond, Instruction &I);
+ Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
+ BinaryOperator &I);
+ Instruction *commonCastTransforms(CastInst &CI);
+ Instruction *commonIntCastTransforms(CastInst &CI);
+ Instruction *commonPointerCastTransforms(CastInst &CI);
+ Instruction *visitTrunc(TruncInst &CI);
+ Instruction *visitZExt(ZExtInst &CI);
+ Instruction *visitSExt(SExtInst &CI);
+ Instruction *visitFPTrunc(FPTruncInst &CI);
+ Instruction *visitFPExt(CastInst &CI);
+ Instruction *visitFPToUI(FPToUIInst &FI);
+ Instruction *visitFPToSI(FPToSIInst &FI);
+ Instruction *visitUIToFP(CastInst &CI);
+ Instruction *visitSIToFP(CastInst &CI);
+ Instruction *visitPtrToInt(PtrToIntInst &CI);
+ Instruction *visitIntToPtr(IntToPtrInst &CI);
+ Instruction *visitBitCast(BitCastInst &CI);
+ Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
+ Instruction *FI);
+ Instruction *FoldSelectIntoOp(SelectInst &SI, Value*, Value*);
+ Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
+ Value *A, Value *B, Instruction &Outer,
+ SelectPatternFlavor SPF2, Value *C);
+ Instruction *visitSelectInst(SelectInst &SI);
+ Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
+ Instruction *visitCallInst(CallInst &CI);
+ Instruction *visitInvokeInst(InvokeInst &II);
+
+ Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
+ Instruction *visitPHINode(PHINode &PN);
+ Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
+ Instruction *visitAllocaInst(AllocaInst &AI);
+ Instruction *visitFree(Instruction &FI);
+ Instruction *visitLoadInst(LoadInst &LI);
+ Instruction *visitStoreInst(StoreInst &SI);
+ Instruction *visitBranchInst(BranchInst &BI);
+ Instruction *visitSwitchInst(SwitchInst &SI);
+ Instruction *visitInsertElementInst(InsertElementInst &IE);
+ Instruction *visitExtractElementInst(ExtractElementInst &EI);
+ Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
+ Instruction *visitExtractValueInst(ExtractValueInst &EV);
+
+ // visitInstruction - Specify what to return for unhandled instructions...
+ Instruction *visitInstruction(Instruction &I) { return 0; }
+
+ private:
+ Instruction *visitCallSite(CallSite CS);
+ bool transformConstExprCastCall(CallSite CS);
+ Instruction *transformCallThroughTrampoline(CallSite CS);
+ Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
+ bool DoXform = true);
+ bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS);
+ DbgDeclareInst *hasOneUsePlusDeclare(Value *V);
+
+
+ public:
+ // InsertNewInstBefore - insert an instruction New before instruction Old
+ // in the program. Add the new instruction to the worklist.
+ //
+ Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
+ assert(New && New->getParent() == 0 &&
+ "New instruction already inserted into a basic block!");
+ BasicBlock *BB = Old.getParent();
+ BB->getInstList().insert(&Old, New); // Insert inst
+ Worklist.Add(New);
+ return New;
+ }
+
+ // ReplaceInstUsesWith - This method is to be used when an instruction is
+ // found to be dead, replacable with another preexisting expression. Here
+ // we add all uses of I to the worklist, replace all uses of I with the new
+ // value, then return I, so that the inst combiner will know that I was
+ // modified.
+ //
+ Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
+ Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist.
+
+ // If we are replacing the instruction with itself, this must be in a
+ // segment of unreachable code, so just clobber the instruction.
+ if (&I == V)
+ V = UndefValue::get(I.getType());
+
+ I.replaceAllUsesWith(V);
+ return &I;
+ }
+
+ // EraseInstFromFunction - When dealing with an instruction that has side
+ // effects or produces a void value, we can't rely on DCE to delete the
+ // instruction. Instead, visit methods should return the value returned by
+ // this function.
+ Instruction *EraseInstFromFunction(Instruction &I) {
+ DEBUG(errs() << "IC: ERASE " << I << '\n');
+
+ assert(I.use_empty() && "Cannot erase instruction that is used!");
+ // Make sure that we reprocess all operands now that we reduced their
+ // use counts.
+ if (I.getNumOperands() < 8) {
+ for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
+ if (Instruction *Op = dyn_cast<Instruction>(*i))
+ Worklist.Add(Op);
+ }
+ Worklist.Remove(&I);
+ I.eraseFromParent();
+ MadeIRChange = true;
+ return 0; // Don't do anything with FI
+ }
+
+ void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
+ APInt &KnownOne, unsigned Depth = 0) const {
+ return llvm::ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth);
+ }
+
+ bool MaskedValueIsZero(Value *V, const APInt &Mask,
+ unsigned Depth = 0) const {
+ return llvm::MaskedValueIsZero(V, Mask, TD, Depth);
+ }
+ unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const {
+ return llvm::ComputeNumSignBits(Op, TD, Depth);
+ }
+
+ private:
+
+ /// SimplifyCommutative - This performs a few simplifications for
+ /// commutative operators.
+ bool SimplifyCommutative(BinaryOperator &I);
+
+ /// SimplifyDemandedUseBits - Attempts to replace V with a simpler value
+ /// based on the demanded bits.
+ Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
+ APInt& KnownZero, APInt& KnownOne,
+ unsigned Depth);
+ bool SimplifyDemandedBits(Use &U, APInt DemandedMask,
+ APInt& KnownZero, APInt& KnownOne,
+ unsigned Depth=0);
+
+ /// SimplifyDemandedInstructionBits - Inst is an integer instruction that
+ /// SimplifyDemandedBits knows about. See if the instruction has any
+ /// properties that allow us to simplify its operands.
+ bool SimplifyDemandedInstructionBits(Instruction &Inst);
+
+ Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
+ APInt& UndefElts, unsigned Depth = 0);
+
+ // FoldOpIntoPhi - Given a binary operator, cast instruction, or select
+ // which has a PHI node as operand #0, see if we can fold the instruction
+ // into the PHI (which is only possible if all operands to the PHI are
+ // constants).
+ //
+ // If AllowAggressive is true, FoldOpIntoPhi will allow certain transforms
+ // that would normally be unprofitable because they strongly encourage jump
+ // threading.
+ Instruction *FoldOpIntoPhi(Instruction &I, bool AllowAggressive = false);
+
+ // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
+ // operator and they all are only used by the PHI, PHI together their
+ // inputs, and do the operation once, to the result of the PHI.
+ Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
+ Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
+ Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
+ Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN);
+
+
+ Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
+ ConstantInt *AndRHS, BinaryOperator &TheAnd);
+
+ Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
+ bool isSub, Instruction &I);
+ Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
+ bool isSigned, bool Inside, Instruction &IB);
+ Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI);
+ Instruction *MatchBSwap(BinaryOperator &I);
+ bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
+ Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
+ Instruction *SimplifyMemSet(MemSetInst *MI);
+
+
+ Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
+
+ bool CanEvaluateInDifferentType(Value *V, const Type *Ty,
+ unsigned CastOpc, int &NumCastsRemoved);
+ unsigned GetOrEnforceKnownAlignment(Value *V,
+ unsigned PrefAlign = 0);
+
+ };
+} // end anonymous namespace
+
+char InstCombiner::ID = 0;
+static RegisterPass<InstCombiner>
+X("instcombine", "Combine redundant instructions");
+
+// getComplexity: Assign a complexity or rank value to LLVM Values...
+// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
+static unsigned getComplexity(Value *V) {
+ if (isa<Instruction>(V)) {
+ if (BinaryOperator::isNeg(V) ||
+ BinaryOperator::isFNeg(V) ||
+ BinaryOperator::isNot(V))
+ return 3;
+ return 4;
+ }
+ if (isa<Argument>(V)) return 3;
+ return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
+}
+
+// isOnlyUse - Return true if this instruction will be deleted if we stop using
+// it.
+static bool isOnlyUse(Value *V) {
+ return V->hasOneUse() || isa<Constant>(V);
+}
+
+// getPromotedType - Return the specified type promoted as it would be to pass
+// though a va_arg area...
+static const Type *getPromotedType(const Type *Ty) {
+ if (const IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
+ if (ITy->getBitWidth() < 32)
+ return Type::getInt32Ty(Ty->getContext());
+ }
+ return Ty;
+}
+
+/// ShouldChangeType - Return true if it is desirable to convert a computation
+/// from 'From' to 'To'. We don't want to convert from a legal to an illegal
+/// type for example, or from a smaller to a larger illegal type.
+static bool ShouldChangeType(const Type *From, const Type *To,
+ const TargetData *TD) {
+ assert(isa<IntegerType>(From) && isa<IntegerType>(To));
+
+ // If we don't have TD, we don't know if the source/dest are legal.
+ if (!TD) return false;
+
+ unsigned FromWidth = From->getPrimitiveSizeInBits();
+ unsigned ToWidth = To->getPrimitiveSizeInBits();
+ bool FromLegal = TD->isLegalInteger(FromWidth);
+ bool ToLegal = TD->isLegalInteger(ToWidth);
+
+ // If this is a legal integer from type, and the result would be an illegal
+ // type, don't do the transformation.
+ if (FromLegal && !ToLegal)
+ return false;
+
+ // Otherwise, if both are illegal, do not increase the size of the result. We
+ // do allow things like i160 -> i64, but not i64 -> i160.
+ if (!FromLegal && !ToLegal && ToWidth > FromWidth)
+ return false;
+
+ return true;
+}
+
+/// getBitCastOperand - If the specified operand is a CastInst, a constant
+/// expression bitcast, or a GetElementPtrInst with all zero indices, return the
+/// operand value, otherwise return null.
+static Value *getBitCastOperand(Value *V) {
+ if (Operator *O = dyn_cast<Operator>(V)) {
+ if (O->getOpcode() == Instruction::BitCast)
+ return O->getOperand(0);
+ if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
+ if (GEP->hasAllZeroIndices())
+ return GEP->getPointerOperand();
+ }
+ return 0;
+}
+
+/// This function is a wrapper around CastInst::isEliminableCastPair. It
+/// simply extracts arguments and returns what that function returns.
+static Instruction::CastOps
+isEliminableCastPair(
+ const CastInst *CI, ///< The first cast instruction
+ unsigned opcode, ///< The opcode of the second cast instruction
+ const Type *DstTy, ///< The target type for the second cast instruction
+ TargetData *TD ///< The target data for pointer size
+) {
+
+ const Type *SrcTy = CI->getOperand(0)->getType(); // A from above
+ const Type *MidTy = CI->getType(); // B from above
+
+ // Get the opcodes of the two Cast instructions
+ Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
+ Instruction::CastOps secondOp = Instruction::CastOps(opcode);
+
+ unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
+ DstTy,
+ TD ? TD->getIntPtrType(CI->getContext()) : 0);
+
+ // We don't want to form an inttoptr or ptrtoint that converts to an integer
+ // type that differs from the pointer size.
+ if ((Res == Instruction::IntToPtr &&
+ (!TD || SrcTy != TD->getIntPtrType(CI->getContext()))) ||
+ (Res == Instruction::PtrToInt &&
+ (!TD || DstTy != TD->getIntPtrType(CI->getContext()))))
+ Res = 0;
+
+ return Instruction::CastOps(Res);
+}
+
+/// ValueRequiresCast - Return true if the cast from "V to Ty" actually results
+/// in any code being generated. It does not require codegen if V is simple
+/// enough or if the cast can be folded into other casts.
+static bool ValueRequiresCast(Instruction::CastOps opcode, const Value *V,
+ const Type *Ty, TargetData *TD) {
+ if (V->getType() == Ty || isa<Constant>(V)) return false;
+
+ // If this is another cast that can be eliminated, it isn't codegen either.
+ if (const CastInst *CI = dyn_cast<CastInst>(V))
+ if (isEliminableCastPair(CI, opcode, Ty, TD))
+ return false;
+ return true;
+}
+
+// SimplifyCommutative - This performs a few simplifications for commutative
+// operators:
+//
+// 1. Order operands such that they are listed from right (least complex) to
+// left (most complex). This puts constants before unary operators before
+// binary operators.
+//
+// 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
+// 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
+//
+bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
+ bool Changed = false;
+ if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
+ Changed = !I.swapOperands();
+
+ if (!I.isAssociative()) return Changed;
+ Instruction::BinaryOps Opcode = I.getOpcode();
+ if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
+ if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
+ if (isa<Constant>(I.getOperand(1))) {
+ Constant *Folded = ConstantExpr::get(I.getOpcode(),
+ cast<Constant>(I.getOperand(1)),
+ cast<Constant>(Op->getOperand(1)));
+ I.setOperand(0, Op->getOperand(0));
+ I.setOperand(1, Folded);
+ return true;
+ } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
+ if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
+ isOnlyUse(Op) && isOnlyUse(Op1)) {
+ Constant *C1 = cast<Constant>(Op->getOperand(1));
+ Constant *C2 = cast<Constant>(Op1->getOperand(1));
+
+ // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
+ Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
+ Instruction *New = BinaryOperator::Create(Opcode, Op->getOperand(0),
+ Op1->getOperand(0),
+ Op1->getName(), &I);
+ Worklist.Add(New);
+ I.setOperand(0, New);
+ I.setOperand(1, Folded);
+ return true;
+ }
+ }
+ return Changed;
+}
+
+// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
+// if the LHS is a constant zero (which is the 'negate' form).
+//
+static inline Value *dyn_castNegVal(Value *V) {
+ if (BinaryOperator::isNeg(V))
+ return BinaryOperator::getNegArgument(V);
+
+ // Constants can be considered to be negated values if they can be folded.
+ if (ConstantInt *C = dyn_cast<ConstantInt>(V))
+ return ConstantExpr::getNeg(C);
+
+ if (ConstantVector *C = dyn_cast<ConstantVector>(V))
+ if (C->getType()->getElementType()->isInteger())
+ return ConstantExpr::getNeg(C);
+
+ return 0;
+}
+
+// dyn_castFNegVal - Given a 'fsub' instruction, return the RHS of the
+// instruction if the LHS is a constant negative zero (which is the 'negate'
+// form).
+//
+static inline Value *dyn_castFNegVal(Value *V) {
+ if (BinaryOperator::isFNeg(V))
+ return BinaryOperator::getFNegArgument(V);
+
+ // Constants can be considered to be negated values if they can be folded.
+ if (ConstantFP *C = dyn_cast<ConstantFP>(V))
+ return ConstantExpr::getFNeg(C);
+
+ if (ConstantVector *C = dyn_cast<ConstantVector>(V))
+ if (C->getType()->getElementType()->isFloatingPoint())
+ return ConstantExpr::getFNeg(C);
+
+ return 0;
+}
+
+/// MatchSelectPattern - Pattern match integer [SU]MIN, [SU]MAX, and ABS idioms,
+/// returning the kind and providing the out parameter results if we
+/// successfully match.
+static SelectPatternFlavor
+MatchSelectPattern(Value *V, Value *&LHS, Value *&RHS) {
+ SelectInst *SI = dyn_cast<SelectInst>(V);
+ if (SI == 0) return SPF_UNKNOWN;
+
+ ICmpInst *ICI = dyn_cast<ICmpInst>(SI->getCondition());
+ if (ICI == 0) return SPF_UNKNOWN;
+
+ LHS = ICI->getOperand(0);
+ RHS = ICI->getOperand(1);
+
+ // (icmp X, Y) ? X : Y
+ if (SI->getTrueValue() == ICI->getOperand(0) &&
+ SI->getFalseValue() == ICI->getOperand(1)) {
+ switch (ICI->getPredicate()) {
+ default: return SPF_UNKNOWN; // Equality.
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_UGE: return SPF_UMAX;
+ case ICmpInst::ICMP_SGT:
+ case ICmpInst::ICMP_SGE: return SPF_SMAX;
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_ULE: return SPF_UMIN;
+ case ICmpInst::ICMP_SLT:
+ case ICmpInst::ICMP_SLE: return SPF_SMIN;
+ }
+ }
+
+ // (icmp X, Y) ? Y : X
+ if (SI->getTrueValue() == ICI->getOperand(1) &&
+ SI->getFalseValue() == ICI->getOperand(0)) {
+ switch (ICI->getPredicate()) {
+ default: return SPF_UNKNOWN; // Equality.
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_UGE: return SPF_UMIN;
+ case ICmpInst::ICMP_SGT:
+ case ICmpInst::ICMP_SGE: return SPF_SMIN;
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_ULE: return SPF_UMAX;
+ case ICmpInst::ICMP_SLT:
+ case ICmpInst::ICMP_SLE: return SPF_SMAX;
+ }
+ }
+
+ // TODO: (X > 4) ? X : 5 --> (X >= 5) ? X : 5 --> MAX(X, 5)
+
+ return SPF_UNKNOWN;
+}
+
+/// isFreeToInvert - Return true if the specified value is free to invert (apply
+/// ~ to). This happens in cases where the ~ can be eliminated.
+static inline bool isFreeToInvert(Value *V) {
+ // ~(~(X)) -> X.
+ if (BinaryOperator::isNot(V))
+ return true;
+
+ // Constants can be considered to be not'ed values.
+ if (isa<ConstantInt>(V))
+ return true;
+
+ // Compares can be inverted if they have a single use.
+ if (CmpInst *CI = dyn_cast<CmpInst>(V))
+ return CI->hasOneUse();
+
+ return false;
+}
+
+static inline Value *dyn_castNotVal(Value *V) {
+ // If this is not(not(x)) don't return that this is a not: we want the two
+ // not's to be folded first.
+ if (BinaryOperator::isNot(V)) {
+ Value *Operand = BinaryOperator::getNotArgument(V);
+ if (!isFreeToInvert(Operand))
+ return Operand;
+ }
+
+ // Constants can be considered to be not'ed values...
+ if (ConstantInt *C = dyn_cast<ConstantInt>(V))
+ return ConstantInt::get(C->getType(), ~C->getValue());
+ return 0;
+}
+
+
+
+// dyn_castFoldableMul - If this value is a multiply that can be folded into
+// other computations (because it has a constant operand), return the
+// non-constant operand of the multiply, and set CST to point to the multiplier.
+// Otherwise, return null.
+//
+static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
+ if (V->hasOneUse() && V->getType()->isInteger())
+ if (Instruction *I = dyn_cast<Instruction>(V)) {
+ if (I->getOpcode() == Instruction::Mul)
+ if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
+ return I->getOperand(0);
+ if (I->getOpcode() == Instruction::Shl)
+ if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
+ // The multiplier is really 1 << CST.
+ uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
+ uint32_t CSTVal = CST->getLimitedValue(BitWidth);
+ CST = ConstantInt::get(V->getType()->getContext(),
+ APInt(BitWidth, 1).shl(CSTVal));
+ return I->getOperand(0);
+ }
+ }
+ return 0;
+}
+
+/// AddOne - Add one to a ConstantInt
+static Constant *AddOne(Constant *C) {
+ return ConstantExpr::getAdd(C,
+ ConstantInt::get(C->getType(), 1));
+}
+/// SubOne - Subtract one from a ConstantInt
+static Constant *SubOne(ConstantInt *C) {
+ return ConstantExpr::getSub(C,
+ ConstantInt::get(C->getType(), 1));
+}
+/// MultiplyOverflows - True if the multiply can not be expressed in an int
+/// this size.
+static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
+ uint32_t W = C1->getBitWidth();
+ APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
+ if (sign) {
+ LHSExt.sext(W * 2);
+ RHSExt.sext(W * 2);
+ } else {
+ LHSExt.zext(W * 2);
+ RHSExt.zext(W * 2);
+ }
+
+ APInt MulExt = LHSExt * RHSExt;
+
+ if (!sign)
+ return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
+
+ APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
+ APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
+ return MulExt.slt(Min) || MulExt.sgt(Max);
+}
+
+
+/// ShrinkDemandedConstant - Check to see if the specified operand of the
+/// specified instruction is a constant integer. If so, check to see if there
+/// are any bits set in the constant that are not demanded. If so, shrink the
+/// constant and return true.
+static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
+ APInt Demanded) {
+ assert(I && "No instruction?");
+ assert(OpNo < I->getNumOperands() && "Operand index too large");
+
+ // If the operand is not a constant integer, nothing to do.
+ ConstantInt *OpC = dyn_cast<ConstantInt>(I->getOperand(OpNo));
+ if (!OpC) return false;
+
+ // If there are no bits set that aren't demanded, nothing to do.
+ Demanded.zextOrTrunc(OpC->getValue().getBitWidth());
+ if ((~Demanded & OpC->getValue()) == 0)
+ return false;
+
+ // This instruction is producing bits that are not demanded. Shrink the RHS.
+ Demanded &= OpC->getValue();
+ I->setOperand(OpNo, ConstantInt::get(OpC->getType(), Demanded));
+ return true;
+}
+
+// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
+// set of known zero and one bits, compute the maximum and minimum values that
+// could have the specified known zero and known one bits, returning them in
+// min/max.
+static void ComputeSignedMinMaxValuesFromKnownBits(const APInt& KnownZero,
+ const APInt& KnownOne,
+ APInt& Min, APInt& Max) {
+ assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
+ KnownZero.getBitWidth() == Min.getBitWidth() &&
+ KnownZero.getBitWidth() == Max.getBitWidth() &&
+ "KnownZero, KnownOne and Min, Max must have equal bitwidth.");
+ APInt UnknownBits = ~(KnownZero|KnownOne);
+
+ // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
+ // bit if it is unknown.
+ Min = KnownOne;
+ Max = KnownOne|UnknownBits;
+
+ if (UnknownBits.isNegative()) { // Sign bit is unknown
+ Min.set(Min.getBitWidth()-1);
+ Max.clear(Max.getBitWidth()-1);
+ }
+}
+
+// ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
+// a set of known zero and one bits, compute the maximum and minimum values that
+// could have the specified known zero and known one bits, returning them in
+// min/max.
+static void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero,
+ const APInt &KnownOne,
+ APInt &Min, APInt &Max) {
+ assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
+ KnownZero.getBitWidth() == Min.getBitWidth() &&
+ KnownZero.getBitWidth() == Max.getBitWidth() &&
+ "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
+ APInt UnknownBits = ~(KnownZero|KnownOne);
+
+ // The minimum value is when the unknown bits are all zeros.
+ Min = KnownOne;
+ // The maximum value is when the unknown bits are all ones.
+ Max = KnownOne|UnknownBits;
+}
+
+/// SimplifyDemandedInstructionBits - Inst is an integer instruction that
+/// SimplifyDemandedBits knows about. See if the instruction has any
+/// properties that allow us to simplify its operands.
+bool InstCombiner::SimplifyDemandedInstructionBits(Instruction &Inst) {
+ unsigned BitWidth = Inst.getType()->getScalarSizeInBits();
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ APInt DemandedMask(APInt::getAllOnesValue(BitWidth));
+
+ Value *V = SimplifyDemandedUseBits(&Inst, DemandedMask,
+ KnownZero, KnownOne, 0);
+ if (V == 0) return false;
+ if (V == &Inst) return true;
+ ReplaceInstUsesWith(Inst, V);
+ return true;
+}
+
+/// SimplifyDemandedBits - This form of SimplifyDemandedBits simplifies the
+/// specified instruction operand if possible, updating it in place. It returns
+/// true if it made any change and false otherwise.
+bool InstCombiner::SimplifyDemandedBits(Use &U, APInt DemandedMask,
+ APInt &KnownZero, APInt &KnownOne,
+ unsigned Depth) {
+ Value *NewVal = SimplifyDemandedUseBits(U.get(), DemandedMask,
+ KnownZero, KnownOne, Depth);
+ if (NewVal == 0) return false;
+ U = NewVal;
+ return true;
+}
+
+
+/// SimplifyDemandedUseBits - This function attempts to replace V with a simpler
+/// value based on the demanded bits. When this function is called, it is known
+/// that only the bits set in DemandedMask of the result of V are ever used
+/// downstream. Consequently, depending on the mask and V, it may be possible
+/// to replace V with a constant or one of its operands. In such cases, this
+/// function does the replacement and returns true. In all other cases, it
+/// returns false after analyzing the expression and setting KnownOne and known
+/// to be one in the expression. KnownZero contains all the bits that are known
+/// to be zero in the expression. These are provided to potentially allow the
+/// caller (which might recursively be SimplifyDemandedBits itself) to simplify
+/// the expression. KnownOne and KnownZero always follow the invariant that
+/// KnownOne & KnownZero == 0. That is, a bit can't be both 1 and 0. Note that
+/// the bits in KnownOne and KnownZero may only be accurate for those bits set
+/// in DemandedMask. Note also that the bitwidth of V, DemandedMask, KnownZero
+/// and KnownOne must all be the same.
+///
+/// This returns null if it did not change anything and it permits no
+/// simplification. This returns V itself if it did some simplification of V's
+/// operands based on the information about what bits are demanded. This returns
+/// some other non-null value if it found out that V is equal to another value
+/// in the context where the specified bits are demanded, but not for all users.
+Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
+ APInt &KnownZero, APInt &KnownOne,
+ unsigned Depth) {
+ assert(V != 0 && "Null pointer of Value???");
+ assert(Depth <= 6 && "Limit Search Depth");
+ uint32_t BitWidth = DemandedMask.getBitWidth();
+ const Type *VTy = V->getType();
+ assert((TD || !isa<PointerType>(VTy)) &&
+ "SimplifyDemandedBits needs to know bit widths!");
+ assert((!TD || TD->getTypeSizeInBits(VTy->getScalarType()) == BitWidth) &&
+ (!VTy->isIntOrIntVector() ||
+ VTy->getScalarSizeInBits() == BitWidth) &&
+ KnownZero.getBitWidth() == BitWidth &&
+ KnownOne.getBitWidth() == BitWidth &&
+ "Value *V, DemandedMask, KnownZero and KnownOne "
+ "must have same BitWidth");
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
+ // We know all of the bits for a constant!
+ KnownOne = CI->getValue() & DemandedMask;
+ KnownZero = ~KnownOne & DemandedMask;
+ return 0;
+ }
+ if (isa<ConstantPointerNull>(V)) {
+ // We know all of the bits for a constant!
+ KnownOne.clear();
+ KnownZero = DemandedMask;
+ return 0;
+ }
+
+ KnownZero.clear();
+ KnownOne.clear();
+ if (DemandedMask == 0) { // Not demanding any bits from V.
+ if (isa<UndefValue>(V))
+ return 0;
+ return UndefValue::get(VTy);
+ }
+
+ if (Depth == 6) // Limit search depth.
+ return 0;
+
+ APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0);
+ APInt &RHSKnownZero = KnownZero, &RHSKnownOne = KnownOne;
+
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) {
+ ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
+ return 0; // Only analyze instructions.
+ }
+
+ // If there are multiple uses of this value and we aren't at the root, then
+ // we can't do any simplifications of the operands, because DemandedMask
+ // only reflects the bits demanded by *one* of the users.
+ if (Depth != 0 && !I->hasOneUse()) {
+ // Despite the fact that we can't simplify this instruction in all User's
+ // context, we can at least compute the knownzero/knownone bits, and we can
+ // do simplifications that apply to *just* the one user if we know that
+ // this instruction has a simpler value in that context.
+ if (I->getOpcode() == Instruction::And) {
+ // If either the LHS or the RHS are Zero, the result is zero.
+ ComputeMaskedBits(I->getOperand(1), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1);
+ ComputeMaskedBits(I->getOperand(0), DemandedMask & ~RHSKnownZero,
+ LHSKnownZero, LHSKnownOne, Depth+1);
+
+ // If all of the demanded bits are known 1 on one side, return the other.
+ // These bits cannot contribute to the result of the 'and' in this
+ // context.
+ if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) ==
+ (DemandedMask & ~LHSKnownZero))
+ return I->getOperand(0);
+ if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) ==
+ (DemandedMask & ~RHSKnownZero))
+ return I->getOperand(1);
+
+ // If all of the demanded bits in the inputs are known zeros, return zero.
+ if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
+ return Constant::getNullValue(VTy);
+
+ } else if (I->getOpcode() == Instruction::Or) {
+ // We can simplify (X|Y) -> X or Y in the user's context if we know that
+ // only bits from X or Y are demanded.
+
+ // If either the LHS or the RHS are One, the result is One.
+ ComputeMaskedBits(I->getOperand(1), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1);
+ ComputeMaskedBits(I->getOperand(0), DemandedMask & ~RHSKnownOne,
+ LHSKnownZero, LHSKnownOne, Depth+1);
+
+ // If all of the demanded bits are known zero on one side, return the
+ // other. These bits cannot contribute to the result of the 'or' in this
+ // context.
+ if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) ==
+ (DemandedMask & ~LHSKnownOne))
+ return I->getOperand(0);
+ if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) ==
+ (DemandedMask & ~RHSKnownOne))
+ return I->getOperand(1);
+
+ // If all of the potentially set bits on one side are known to be set on
+ // the other side, just use the 'other' side.
+ if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) ==
+ (DemandedMask & (~RHSKnownZero)))
+ return I->getOperand(0);
+ if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) ==
+ (DemandedMask & (~LHSKnownZero)))
+ return I->getOperand(1);
+ }
+
+ // Compute the KnownZero/KnownOne bits to simplify things downstream.
+ ComputeMaskedBits(I, DemandedMask, KnownZero, KnownOne, Depth);
+ return 0;
+ }
+
+ // If this is the root being simplified, allow it to have multiple uses,
+ // just set the DemandedMask to all bits so that we can try to simplify the
+ // operands. This allows visitTruncInst (for example) to simplify the
+ // operand of a trunc without duplicating all the logic below.
+ if (Depth == 0 && !V->hasOneUse())
+ DemandedMask = APInt::getAllOnesValue(BitWidth);
+
+ switch (I->getOpcode()) {
+ default:
+ ComputeMaskedBits(I, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
+ break;
+ case Instruction::And:
+ // If either the LHS or the RHS are Zero, the result is zero.
+ if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1) ||
+ SimplifyDemandedBits(I->getOperandUse(0), DemandedMask & ~RHSKnownZero,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return I;
+ assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+ assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
+
+ // If all of the demanded bits are known 1 on one side, return the other.
+ // These bits cannot contribute to the result of the 'and'.
+ if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) ==
+ (DemandedMask & ~LHSKnownZero))
+ return I->getOperand(0);
+ if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) ==
+ (DemandedMask & ~RHSKnownZero))
+ return I->getOperand(1);
+
+ // If all of the demanded bits in the inputs are known zeros, return zero.
+ if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
+ return Constant::getNullValue(VTy);
+
+ // If the RHS is a constant, see if we can simplify it.
+ if (ShrinkDemandedConstant(I, 1, DemandedMask & ~LHSKnownZero))
+ return I;
+
+ // Output known-1 bits are only known if set in both the LHS & RHS.
+ RHSKnownOne &= LHSKnownOne;
+ // Output known-0 are known to be clear if zero in either the LHS | RHS.
+ RHSKnownZero |= LHSKnownZero;
+ break;
+ case Instruction::Or:
+ // If either the LHS or the RHS are One, the result is One.
+ if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1) ||
+ SimplifyDemandedBits(I->getOperandUse(0), DemandedMask & ~RHSKnownOne,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return I;
+ assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+ assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
+
+ // If all of the demanded bits are known zero on one side, return the other.
+ // These bits cannot contribute to the result of the 'or'.
+ if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) ==
+ (DemandedMask & ~LHSKnownOne))
+ return I->getOperand(0);
+ if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) ==
+ (DemandedMask & ~RHSKnownOne))
+ return I->getOperand(1);
+
+ // If all of the potentially set bits on one side are known to be set on
+ // the other side, just use the 'other' side.
+ if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) ==
+ (DemandedMask & (~RHSKnownZero)))
+ return I->getOperand(0);
+ if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) ==
+ (DemandedMask & (~LHSKnownZero)))
+ return I->getOperand(1);
+
+ // If the RHS is a constant, see if we can simplify it.
+ if (ShrinkDemandedConstant(I, 1, DemandedMask))
+ return I;
+
+ // Output known-0 bits are only known if clear in both the LHS & RHS.
+ RHSKnownZero &= LHSKnownZero;
+ // Output known-1 are known to be set if set in either the LHS | RHS.
+ RHSKnownOne |= LHSKnownOne;
+ break;
+ case Instruction::Xor: {
+ if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1) ||
+ SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return I;
+ assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+ assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
+
+ // If all of the demanded bits are known zero on one side, return the other.
+ // These bits cannot contribute to the result of the 'xor'.
+ if ((DemandedMask & RHSKnownZero) == DemandedMask)
+ return I->getOperand(0);
+ if ((DemandedMask & LHSKnownZero) == DemandedMask)
+ return I->getOperand(1);
+
+ // Output known-0 bits are known if clear or set in both the LHS & RHS.
+ APInt KnownZeroOut = (RHSKnownZero & LHSKnownZero) |
+ (RHSKnownOne & LHSKnownOne);
+ // Output known-1 are known to be set if set in only one of the LHS, RHS.
+ APInt KnownOneOut = (RHSKnownZero & LHSKnownOne) |
+ (RHSKnownOne & LHSKnownZero);
+
+ // If all of the demanded bits are known to be zero on one side or the
+ // other, turn this into an *inclusive* or.
+ // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
+ if ((DemandedMask & ~RHSKnownZero & ~LHSKnownZero) == 0) {
+ Instruction *Or =
+ BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1),
+ I->getName());
+ return InsertNewInstBefore(Or, *I);
+ }
+
+ // If all of the demanded bits on one side are known, and all of the set
+ // bits on that side are also known to be set on the other side, turn this
+ // into an AND, as we know the bits will be cleared.
+ // e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
+ if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask) {
+ // all known
+ if ((RHSKnownOne & LHSKnownOne) == RHSKnownOne) {
+ Constant *AndC = Constant::getIntegerValue(VTy,
+ ~RHSKnownOne & DemandedMask);
+ Instruction *And =
+ BinaryOperator::CreateAnd(I->getOperand(0), AndC, "tmp");
+ return InsertNewInstBefore(And, *I);
+ }
+ }
+
+ // If the RHS is a constant, see if we can simplify it.
+ // FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
+ if (ShrinkDemandedConstant(I, 1, DemandedMask))
+ return I;
+
+ // If our LHS is an 'and' and if it has one use, and if any of the bits we
+ // are flipping are known to be set, then the xor is just resetting those
+ // bits to zero. We can just knock out bits from the 'and' and the 'xor',
+ // simplifying both of them.
+ if (Instruction *LHSInst = dyn_cast<Instruction>(I->getOperand(0)))
+ if (LHSInst->getOpcode() == Instruction::And && LHSInst->hasOneUse() &&
+ isa<ConstantInt>(I->getOperand(1)) &&
+ isa<ConstantInt>(LHSInst->getOperand(1)) &&
+ (LHSKnownOne & RHSKnownOne & DemandedMask) != 0) {
+ ConstantInt *AndRHS = cast<ConstantInt>(LHSInst->getOperand(1));
+ ConstantInt *XorRHS = cast<ConstantInt>(I->getOperand(1));
+ APInt NewMask = ~(LHSKnownOne & RHSKnownOne & DemandedMask);
+
+ Constant *AndC =
+ ConstantInt::get(I->getType(), NewMask & AndRHS->getValue());
+ Instruction *NewAnd =
+ BinaryOperator::CreateAnd(I->getOperand(0), AndC, "tmp");
+ InsertNewInstBefore(NewAnd, *I);
+
+ Constant *XorC =
+ ConstantInt::get(I->getType(), NewMask & XorRHS->getValue());
+ Instruction *NewXor =
+ BinaryOperator::CreateXor(NewAnd, XorC, "tmp");
+ return InsertNewInstBefore(NewXor, *I);
+ }
+
+
+ RHSKnownZero = KnownZeroOut;
+ RHSKnownOne = KnownOneOut;
+ break;
+ }
+ case Instruction::Select:
+ if (SimplifyDemandedBits(I->getOperandUse(2), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1) ||
+ SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return I;
+ assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+ assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
+
+ // If the operands are constants, see if we can simplify them.
+ if (ShrinkDemandedConstant(I, 1, DemandedMask) ||
+ ShrinkDemandedConstant(I, 2, DemandedMask))
+ return I;
+
+ // Only known if known in both the LHS and RHS.
+ RHSKnownOne &= LHSKnownOne;
+ RHSKnownZero &= LHSKnownZero;
+ break;
+ case Instruction::Trunc: {
+ unsigned truncBf = I->getOperand(0)->getType()->getScalarSizeInBits();
+ DemandedMask.zext(truncBf);
+ RHSKnownZero.zext(truncBf);
+ RHSKnownOne.zext(truncBf);
+ if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return I;
+ DemandedMask.trunc(BitWidth);
+ RHSKnownZero.trunc(BitWidth);
+ RHSKnownOne.trunc(BitWidth);
+ assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+ break;
+ }
+ case Instruction::BitCast:
+ if (!I->getOperand(0)->getType()->isIntOrIntVector())
+ return false; // vector->int or fp->int?
+
+ if (const VectorType *DstVTy = dyn_cast<VectorType>(I->getType())) {
+ if (const VectorType *SrcVTy =
+ dyn_cast<VectorType>(I->getOperand(0)->getType())) {
+ if (DstVTy->getNumElements() != SrcVTy->getNumElements())
+ // Don't touch a bitcast between vectors of different element counts.
+ return false;
+ } else
+ // Don't touch a scalar-to-vector bitcast.
+ return false;
+ } else if (isa<VectorType>(I->getOperand(0)->getType()))
+ // Don't touch a vector-to-scalar bitcast.
+ return false;
+
+ if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return I;
+ assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+ break;
+ case Instruction::ZExt: {
+ // Compute the bits in the result that are not present in the input.
+ unsigned SrcBitWidth =I->getOperand(0)->getType()->getScalarSizeInBits();
+
+ DemandedMask.trunc(SrcBitWidth);
+ RHSKnownZero.trunc(SrcBitWidth);
+ RHSKnownOne.trunc(SrcBitWidth);
+ if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return I;
+ DemandedMask.zext(BitWidth);
+ RHSKnownZero.zext(BitWidth);
+ RHSKnownOne.zext(BitWidth);
+ assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+ // The top bits are known to be zero.
+ RHSKnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
+ break;
+ }
+ case Instruction::SExt: {
+ // Compute the bits in the result that are not present in the input.
+ unsigned SrcBitWidth =I->getOperand(0)->getType()->getScalarSizeInBits();
+
+ APInt InputDemandedBits = DemandedMask &
+ APInt::getLowBitsSet(BitWidth, SrcBitWidth);
+
+ APInt NewBits(APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth));
+ // If any of the sign extended bits are demanded, we know that the sign
+ // bit is demanded.
+ if ((NewBits & DemandedMask) != 0)
+ InputDemandedBits.set(SrcBitWidth-1);
+
+ InputDemandedBits.trunc(SrcBitWidth);
+ RHSKnownZero.trunc(SrcBitWidth);
+ RHSKnownOne.trunc(SrcBitWidth);
+ if (SimplifyDemandedBits(I->getOperandUse(0), InputDemandedBits,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return I;
+ InputDemandedBits.zext(BitWidth);
+ RHSKnownZero.zext(BitWidth);
+ RHSKnownOne.zext(BitWidth);
+ assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+
+ // If the sign bit of the input is known set or clear, then we know the
+ // top bits of the result.
+
+ // If the input sign bit is known zero, or if the NewBits are not demanded
+ // convert this into a zero extension.
+ if (RHSKnownZero[SrcBitWidth-1] || (NewBits & ~DemandedMask) == NewBits) {
+ // Convert to ZExt cast
+ CastInst *NewCast = new ZExtInst(I->getOperand(0), VTy, I->getName());
+ return InsertNewInstBefore(NewCast, *I);
+ } else if (RHSKnownOne[SrcBitWidth-1]) { // Input sign bit known set
+ RHSKnownOne |= NewBits;
+ }
+ break;
+ }
+ case Instruction::Add: {
+ // Figure out what the input bits are. If the top bits of the and result
+ // are not demanded, then the add doesn't demand them from its input
+ // either.
+ unsigned NLZ = DemandedMask.countLeadingZeros();
+
+ // If there is a constant on the RHS, there are a variety of xformations
+ // we can do.
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ // If null, this should be simplified elsewhere. Some of the xforms here
+ // won't work if the RHS is zero.
+ if (RHS->isZero())
+ break;
+
+ // If the top bit of the output is demanded, demand everything from the
+ // input. Otherwise, we demand all the input bits except NLZ top bits.
+ APInt InDemandedBits(APInt::getLowBitsSet(BitWidth, BitWidth - NLZ));
+
+ // Find information about known zero/one bits in the input.
+ if (SimplifyDemandedBits(I->getOperandUse(0), InDemandedBits,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return I;
+
+ // If the RHS of the add has bits set that can't affect the input, reduce
+ // the constant.
+ if (ShrinkDemandedConstant(I, 1, InDemandedBits))
+ return I;
+
+ // Avoid excess work.
+ if (LHSKnownZero == 0 && LHSKnownOne == 0)
+ break;
+
+ // Turn it into OR if input bits are zero.
+ if ((LHSKnownZero & RHS->getValue()) == RHS->getValue()) {
+ Instruction *Or =
+ BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1),
+ I->getName());
+ return InsertNewInstBefore(Or, *I);
+ }
+
+ // We can say something about the output known-zero and known-one bits,
+ // depending on potential carries from the input constant and the
+ // unknowns. For example if the LHS is known to have at most the 0x0F0F0
+ // bits set and the RHS constant is 0x01001, then we know we have a known
+ // one mask of 0x00001 and a known zero mask of 0xE0F0E.
+
+ // To compute this, we first compute the potential carry bits. These are
+ // the bits which may be modified. I'm not aware of a better way to do
+ // this scan.
+ const APInt &RHSVal = RHS->getValue();
+ APInt CarryBits((~LHSKnownZero + RHSVal) ^ (~LHSKnownZero ^ RHSVal));
+
+ // Now that we know which bits have carries, compute the known-1/0 sets.
+
+ // Bits are known one if they are known zero in one operand and one in the
+ // other, and there is no input carry.
+ RHSKnownOne = ((LHSKnownZero & RHSVal) |
+ (LHSKnownOne & ~RHSVal)) & ~CarryBits;
+
+ // Bits are known zero if they are known zero in both operands and there
+ // is no input carry.
+ RHSKnownZero = LHSKnownZero & ~RHSVal & ~CarryBits;
+ } else {
+ // If the high-bits of this ADD are not demanded, then it does not demand
+ // the high bits of its LHS or RHS.
+ if (DemandedMask[BitWidth-1] == 0) {
+ // Right fill the mask of bits for this ADD to demand the most
+ // significant bit and all those below it.
+ APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
+ if (SimplifyDemandedBits(I->getOperandUse(0), DemandedFromOps,
+ LHSKnownZero, LHSKnownOne, Depth+1) ||
+ SimplifyDemandedBits(I->getOperandUse(1), DemandedFromOps,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return I;
+ }
+ }
+ break;
+ }
+ case Instruction::Sub:
+ // If the high-bits of this SUB are not demanded, then it does not demand
+ // the high bits of its LHS or RHS.
+ if (DemandedMask[BitWidth-1] == 0) {
+ // Right fill the mask of bits for this SUB to demand the most
+ // significant bit and all those below it.
+ uint32_t NLZ = DemandedMask.countLeadingZeros();
+ APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
+ if (SimplifyDemandedBits(I->getOperandUse(0), DemandedFromOps,
+ LHSKnownZero, LHSKnownOne, Depth+1) ||
+ SimplifyDemandedBits(I->getOperandUse(1), DemandedFromOps,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return I;
+ }
+ // Otherwise just hand the sub off to ComputeMaskedBits to fill in
+ // the known zeros and ones.
+ ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
+ break;
+ case Instruction::Shl:
+ if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
+ APInt DemandedMaskIn(DemandedMask.lshr(ShiftAmt));
+ if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return I;
+ assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+ RHSKnownZero <<= ShiftAmt;
+ RHSKnownOne <<= ShiftAmt;
+ // low bits known zero.
+ if (ShiftAmt)
+ RHSKnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt);
+ }
+ break;
+ case Instruction::LShr:
+ // For a logical shift right
+ if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
+
+ // Unsigned shift right.
+ APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
+ if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return I;
+ assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+ RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
+ RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
+ if (ShiftAmt) {
+ // Compute the new bits that are at the top now.
+ APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
+ RHSKnownZero |= HighBits; // high bits known zero.
+ }
+ }
+ break;
+ case Instruction::AShr:
+ // If this is an arithmetic shift right and only the low-bit is set, we can
+ // always convert this into a logical shr, even if the shift amount is
+ // variable. The low bit of the shift cannot be an input sign bit unless
+ // the shift amount is >= the size of the datatype, which is undefined.
+ if (DemandedMask == 1) {
+ // Perform the logical shift right.
+ Instruction *NewVal = BinaryOperator::CreateLShr(
+ I->getOperand(0), I->getOperand(1), I->getName());
+ return InsertNewInstBefore(NewVal, *I);
+ }
+
+ // If the sign bit is the only bit demanded by this ashr, then there is no
+ // need to do it, the shift doesn't change the high bit.
+ if (DemandedMask.isSignBit())
+ return I->getOperand(0);
+
+ if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ uint32_t ShiftAmt = SA->getLimitedValue(BitWidth);
+
+ // Signed shift right.
+ APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
+ // If any of the "high bits" are demanded, we should set the sign bit as
+ // demanded.
+ if (DemandedMask.countLeadingZeros() <= ShiftAmt)
+ DemandedMaskIn.set(BitWidth-1);
+ if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return I;
+ assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+ // Compute the new bits that are at the top now.
+ APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
+ RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
+ RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
+
+ // Handle the sign bits.
+ APInt SignBit(APInt::getSignBit(BitWidth));
+ // Adjust to where it is now in the mask.
+ SignBit = APIntOps::lshr(SignBit, ShiftAmt);
+
+ // If the input sign bit is known to be zero, or if none of the top bits
+ // are demanded, turn this into an unsigned shift right.
+ if (BitWidth <= ShiftAmt || RHSKnownZero[BitWidth-ShiftAmt-1] ||
+ (HighBits & ~DemandedMask) == HighBits) {
+ // Perform the logical shift right.
+ Instruction *NewVal = BinaryOperator::CreateLShr(
+ I->getOperand(0), SA, I->getName());
+ return InsertNewInstBefore(NewVal, *I);
+ } else if ((RHSKnownOne & SignBit) != 0) { // New bits are known one.
+ RHSKnownOne |= HighBits;
+ }
+ }
+ break;
+ case Instruction::SRem:
+ if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ APInt RA = Rem->getValue().abs();
+ if (RA.isPowerOf2()) {
+ if (DemandedMask.ult(RA)) // srem won't affect demanded bits
+ return I->getOperand(0);
+
+ APInt LowBits = RA - 1;
+ APInt Mask2 = LowBits | APInt::getSignBit(BitWidth);
+ if (SimplifyDemandedBits(I->getOperandUse(0), Mask2,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return I;
+
+ if (LHSKnownZero[BitWidth-1] || ((LHSKnownZero & LowBits) == LowBits))
+ LHSKnownZero |= ~LowBits;
+
+ KnownZero |= LHSKnownZero & DemandedMask;
+
+ assert(!(KnownZero & KnownOne) && "Bits known to be one AND zero?");
+ }
+ }
+ break;
+ case Instruction::URem: {
+ APInt KnownZero2(BitWidth, 0), KnownOne2(BitWidth, 0);
+ APInt AllOnes = APInt::getAllOnesValue(BitWidth);
+ if (SimplifyDemandedBits(I->getOperandUse(0), AllOnes,
+ KnownZero2, KnownOne2, Depth+1) ||
+ SimplifyDemandedBits(I->getOperandUse(1), AllOnes,
+ KnownZero2, KnownOne2, Depth+1))
+ return I;
+
+ unsigned Leaders = KnownZero2.countLeadingOnes();
+ Leaders = std::max(Leaders,
+ KnownZero2.countLeadingOnes());
+ KnownZero = APInt::getHighBitsSet(BitWidth, Leaders) & DemandedMask;
+ break;
+ }
+ case Instruction::Call:
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
+ switch (II->getIntrinsicID()) {
+ default: break;
+ case Intrinsic::bswap: {
+ // If the only bits demanded come from one byte of the bswap result,
+ // just shift the input byte into position to eliminate the bswap.
+ unsigned NLZ = DemandedMask.countLeadingZeros();
+ unsigned NTZ = DemandedMask.countTrailingZeros();
+
+ // Round NTZ down to the next byte. If we have 11 trailing zeros, then
+ // we need all the bits down to bit 8. Likewise, round NLZ. If we
+ // have 14 leading zeros, round to 8.
+ NLZ &= ~7;
+ NTZ &= ~7;
+ // If we need exactly one byte, we can do this transformation.
+ if (BitWidth-NLZ-NTZ == 8) {
+ unsigned ResultBit = NTZ;
+ unsigned InputBit = BitWidth-NTZ-8;
+
+ // Replace this with either a left or right shift to get the byte into
+ // the right place.
+ Instruction *NewVal;
+ if (InputBit > ResultBit)
+ NewVal = BinaryOperator::CreateLShr(I->getOperand(1),
+ ConstantInt::get(I->getType(), InputBit-ResultBit));
+ else
+ NewVal = BinaryOperator::CreateShl(I->getOperand(1),
+ ConstantInt::get(I->getType(), ResultBit-InputBit));
+ NewVal->takeName(I);
+ return InsertNewInstBefore(NewVal, *I);
+ }
+
+ // TODO: Could compute known zero/one bits based on the input.
+ break;
+ }
+ }
+ }
+ ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
+ break;
+ }
+
+ // If the client is only demanding bits that we know, return the known
+ // constant.
+ if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask)
+ return Constant::getIntegerValue(VTy, RHSKnownOne);
+ return false;
+}
+
+
+/// SimplifyDemandedVectorElts - The specified value produces a vector with
+/// any number of elements. DemandedElts contains the set of elements that are
+/// actually used by the caller. This method analyzes which elements of the
+/// operand are undef and returns that information in UndefElts.
+///
+/// If the information about demanded elements can be used to simplify the
+/// operation, the operation is simplified, then the resultant value is
+/// returned. This returns null if no change was made.
+Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
+ APInt& UndefElts,
+ unsigned Depth) {
+ unsigned VWidth = cast<VectorType>(V->getType())->getNumElements();
+ APInt EltMask(APInt::getAllOnesValue(VWidth));
+ assert((DemandedElts & ~EltMask) == 0 && "Invalid DemandedElts!");
+
+ if (isa<UndefValue>(V)) {
+ // If the entire vector is undefined, just return this info.
+ UndefElts = EltMask;
+ return 0;
+ } else if (DemandedElts == 0) { // If nothing is demanded, provide undef.
+ UndefElts = EltMask;
+ return UndefValue::get(V->getType());
+ }
+
+ UndefElts = 0;
+ if (ConstantVector *CP = dyn_cast<ConstantVector>(V)) {
+ const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
+ Constant *Undef = UndefValue::get(EltTy);
+
+ std::vector<Constant*> Elts;
+ for (unsigned i = 0; i != VWidth; ++i)
+ if (!DemandedElts[i]) { // If not demanded, set to undef.
+ Elts.push_back(Undef);
+ UndefElts.set(i);
+ } else if (isa<UndefValue>(CP->getOperand(i))) { // Already undef.
+ Elts.push_back(Undef);
+ UndefElts.set(i);
+ } else { // Otherwise, defined.
+ Elts.push_back(CP->getOperand(i));
+ }
+
+ // If we changed the constant, return it.
+ Constant *NewCP = ConstantVector::get(Elts);
+ return NewCP != CP ? NewCP : 0;
+ } else if (isa<ConstantAggregateZero>(V)) {
+ // Simplify the CAZ to a ConstantVector where the non-demanded elements are
+ // set to undef.
+
+ // Check if this is identity. If so, return 0 since we are not simplifying
+ // anything.
+ if (DemandedElts == ((1ULL << VWidth) -1))
+ return 0;
+
+ const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
+ Constant *Zero = Constant::getNullValue(EltTy);
+ Constant *Undef = UndefValue::get(EltTy);
+ std::vector<Constant*> Elts;
+ for (unsigned i = 0; i != VWidth; ++i) {
+ Constant *Elt = DemandedElts[i] ? Zero : Undef;
+ Elts.push_back(Elt);
+ }
+ UndefElts = DemandedElts ^ EltMask;
+ return ConstantVector::get(Elts);
+ }
+
+ // Limit search depth.
+ if (Depth == 10)
+ return 0;
+
+ // If multiple users are using the root value, procede with
+ // simplification conservatively assuming that all elements
+ // are needed.
+ if (!V->hasOneUse()) {
+ // Quit if we find multiple users of a non-root value though.
+ // They'll be handled when it's their turn to be visited by
+ // the main instcombine process.
+ if (Depth != 0)
+ // TODO: Just compute the UndefElts information recursively.
+ return 0;
+
+ // Conservatively assume that all elements are needed.
+ DemandedElts = EltMask;
+ }
+
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) return 0; // Only analyze instructions.
+
+ bool MadeChange = false;
+ APInt UndefElts2(VWidth, 0);
+ Value *TmpV;
+ switch (I->getOpcode()) {
+ default: break;
+
+ case Instruction::InsertElement: {
+ // If this is a variable index, we don't know which element it overwrites.
+ // demand exactly the same input as we produce.
+ ConstantInt *Idx = dyn_cast<ConstantInt>(I->getOperand(2));
+ if (Idx == 0) {
+ // Note that we can't propagate undef elt info, because we don't know
+ // which elt is getting updated.
+ TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
+ UndefElts2, Depth+1);
+ if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
+ break;
+ }
+
+ // If this is inserting an element that isn't demanded, remove this
+ // insertelement.
+ unsigned IdxNo = Idx->getZExtValue();
+ if (IdxNo >= VWidth || !DemandedElts[IdxNo]) {
+ Worklist.Add(I);
+ return I->getOperand(0);
+ }
+
+ // Otherwise, the element inserted overwrites whatever was there, so the
+ // input demanded set is simpler than the output set.
+ APInt DemandedElts2 = DemandedElts;
+ DemandedElts2.clear(IdxNo);
+ TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts2,
+ UndefElts, Depth+1);
+ if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
+
+ // The inserted element is defined.
+ UndefElts.clear(IdxNo);
+ break;
+ }
+ case Instruction::ShuffleVector: {
+ ShuffleVectorInst *Shuffle = cast<ShuffleVectorInst>(I);
+ uint64_t LHSVWidth =
+ cast<VectorType>(Shuffle->getOperand(0)->getType())->getNumElements();
+ APInt LeftDemanded(LHSVWidth, 0), RightDemanded(LHSVWidth, 0);
+ for (unsigned i = 0; i < VWidth; i++) {
+ if (DemandedElts[i]) {
+ unsigned MaskVal = Shuffle->getMaskValue(i);
+ if (MaskVal != -1u) {
+ assert(MaskVal < LHSVWidth * 2 &&
+ "shufflevector mask index out of range!");
+ if (MaskVal < LHSVWidth)
+ LeftDemanded.set(MaskVal);
+ else
+ RightDemanded.set(MaskVal - LHSVWidth);
+ }
+ }
+ }
+
+ APInt UndefElts4(LHSVWidth, 0);
+ TmpV = SimplifyDemandedVectorElts(I->getOperand(0), LeftDemanded,
+ UndefElts4, Depth+1);
+ if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
+
+ APInt UndefElts3(LHSVWidth, 0);
+ TmpV = SimplifyDemandedVectorElts(I->getOperand(1), RightDemanded,
+ UndefElts3, Depth+1);
+ if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
+
+ bool NewUndefElts = false;
+ for (unsigned i = 0; i < VWidth; i++) {
+ unsigned MaskVal = Shuffle->getMaskValue(i);
+ if (MaskVal == -1u) {
+ UndefElts.set(i);
+ } else if (MaskVal < LHSVWidth) {
+ if (UndefElts4[MaskVal]) {
+ NewUndefElts = true;
+ UndefElts.set(i);
+ }
+ } else {
+ if (UndefElts3[MaskVal - LHSVWidth]) {
+ NewUndefElts = true;
+ UndefElts.set(i);
+ }
+ }
+ }
+
+ if (NewUndefElts) {
+ // Add additional discovered undefs.
+ std::vector<Constant*> Elts;
+ for (unsigned i = 0; i < VWidth; ++i) {
+ if (UndefElts[i])
+ Elts.push_back(UndefValue::get(Type::getInt32Ty(*Context)));
+ else
+ Elts.push_back(ConstantInt::get(Type::getInt32Ty(*Context),
+ Shuffle->getMaskValue(i)));
+ }
+ I->setOperand(2, ConstantVector::get(Elts));
+ MadeChange = true;
+ }
+ break;
+ }
+ case Instruction::BitCast: {
+ // Vector->vector casts only.
+ const VectorType *VTy = dyn_cast<VectorType>(I->getOperand(0)->getType());
+ if (!VTy) break;
+ unsigned InVWidth = VTy->getNumElements();
+ APInt InputDemandedElts(InVWidth, 0);
+ unsigned Ratio;
+
+ if (VWidth == InVWidth) {
+ // If we are converting from <4 x i32> -> <4 x f32>, we demand the same
+ // elements as are demanded of us.
+ Ratio = 1;
+ InputDemandedElts = DemandedElts;
+ } else if (VWidth > InVWidth) {
+ // Untested so far.
+ break;
+
+ // If there are more elements in the result than there are in the source,
+ // then an input element is live if any of the corresponding output
+ // elements are live.
+ Ratio = VWidth/InVWidth;
+ for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) {
+ if (DemandedElts[OutIdx])
+ InputDemandedElts.set(OutIdx/Ratio);
+ }
+ } else {
+ // Untested so far.
+ break;
+
+ // If there are more elements in the source than there are in the result,
+ // then an input element is live if the corresponding output element is
+ // live.
+ Ratio = InVWidth/VWidth;
+ for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
+ if (DemandedElts[InIdx/Ratio])
+ InputDemandedElts.set(InIdx);
+ }
+
+ // div/rem demand all inputs, because they don't want divide by zero.
+ TmpV = SimplifyDemandedVectorElts(I->getOperand(0), InputDemandedElts,
+ UndefElts2, Depth+1);
+ if (TmpV) {
+ I->setOperand(0, TmpV);
+ MadeChange = true;
+ }
+
+ UndefElts = UndefElts2;
+ if (VWidth > InVWidth) {
+ llvm_unreachable("Unimp");
+ // If there are more elements in the result than there are in the source,
+ // then an output element is undef if the corresponding input element is
+ // undef.
+ for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
+ if (UndefElts2[OutIdx/Ratio])
+ UndefElts.set(OutIdx);
+ } else if (VWidth < InVWidth) {
+ llvm_unreachable("Unimp");
+ // If there are more elements in the source than there are in the result,
+ // then a result element is undef if all of the corresponding input
+ // elements are undef.
+ UndefElts = ~0ULL >> (64-VWidth); // Start out all undef.
+ for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
+ if (!UndefElts2[InIdx]) // Not undef?
+ UndefElts.clear(InIdx/Ratio); // Clear undef bit.
+ }
+ break;
+ }
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Mul:
+ // div/rem demand all inputs, because they don't want divide by zero.
+ TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
+ UndefElts, Depth+1);
+ if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
+ TmpV = SimplifyDemandedVectorElts(I->getOperand(1), DemandedElts,
+ UndefElts2, Depth+1);
+ if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
+
+ // Output elements are undefined if both are undefined. Consider things
+ // like undef&0. The result is known zero, not undef.
+ UndefElts &= UndefElts2;
+ break;
+
+ case Instruction::Call: {
+ IntrinsicInst *II = dyn_cast<IntrinsicInst>(I);
+ if (!II) break;
+ switch (II->getIntrinsicID()) {
+ default: break;
+
+ // Binary vector operations that work column-wise. A dest element is a
+ // function of the corresponding input elements from the two inputs.
+ case Intrinsic::x86_sse_sub_ss:
+ case Intrinsic::x86_sse_mul_ss:
+ case Intrinsic::x86_sse_min_ss:
+ case Intrinsic::x86_sse_max_ss:
+ case Intrinsic::x86_sse2_sub_sd:
+ case Intrinsic::x86_sse2_mul_sd:
+ case Intrinsic::x86_sse2_min_sd:
+ case Intrinsic::x86_sse2_max_sd:
+ TmpV = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
+ UndefElts, Depth+1);
+ if (TmpV) { II->setOperand(1, TmpV); MadeChange = true; }
+ TmpV = SimplifyDemandedVectorElts(II->getOperand(2), DemandedElts,
+ UndefElts2, Depth+1);
+ if (TmpV) { II->setOperand(2, TmpV); MadeChange = true; }
+
+ // If only the low elt is demanded and this is a scalarizable intrinsic,
+ // scalarize it now.
+ if (DemandedElts == 1) {
+ switch (II->getIntrinsicID()) {
+ default: break;
+ case Intrinsic::x86_sse_sub_ss:
+ case Intrinsic::x86_sse_mul_ss:
+ case Intrinsic::x86_sse2_sub_sd:
+ case Intrinsic::x86_sse2_mul_sd:
+ // TODO: Lower MIN/MAX/ABS/etc
+ Value *LHS = II->getOperand(1);
+ Value *RHS = II->getOperand(2);
+ // Extract the element as scalars.
+ LHS = InsertNewInstBefore(ExtractElementInst::Create(LHS,
+ ConstantInt::get(Type::getInt32Ty(*Context), 0U, false), "tmp"), *II);
+ RHS = InsertNewInstBefore(ExtractElementInst::Create(RHS,
+ ConstantInt::get(Type::getInt32Ty(*Context), 0U, false), "tmp"), *II);
+
+ switch (II->getIntrinsicID()) {
+ default: llvm_unreachable("Case stmts out of sync!");
+ case Intrinsic::x86_sse_sub_ss:
+ case Intrinsic::x86_sse2_sub_sd:
+ TmpV = InsertNewInstBefore(BinaryOperator::CreateFSub(LHS, RHS,
+ II->getName()), *II);
+ break;
+ case Intrinsic::x86_sse_mul_ss:
+ case Intrinsic::x86_sse2_mul_sd:
+ TmpV = InsertNewInstBefore(BinaryOperator::CreateFMul(LHS, RHS,
+ II->getName()), *II);
+ break;
+ }
+
+ Instruction *New =
+ InsertElementInst::Create(
+ UndefValue::get(II->getType()), TmpV,
+ ConstantInt::get(Type::getInt32Ty(*Context), 0U, false), II->getName());
+ InsertNewInstBefore(New, *II);
+ return New;
+ }
+ }
+
+ // Output elements are undefined if both are undefined. Consider things
+ // like undef&0. The result is known zero, not undef.
+ UndefElts &= UndefElts2;
+ break;
+ }
+ break;
+ }
+ }
+ return MadeChange ? I : 0;
+}
+
+
+/// AssociativeOpt - Perform an optimization on an associative operator. This
+/// function is designed to check a chain of associative operators for a
+/// potential to apply a certain optimization. Since the optimization may be
+/// applicable if the expression was reassociated, this checks the chain, then
+/// reassociates the expression as necessary to expose the optimization
+/// opportunity. This makes use of a special Functor, which must define
+/// 'shouldApply' and 'apply' methods.
+///
+template<typename Functor>
+static Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
+ unsigned Opcode = Root.getOpcode();
+ Value *LHS = Root.getOperand(0);
+
+ // Quick check, see if the immediate LHS matches...
+ if (F.shouldApply(LHS))
+ return F.apply(Root);
+
+ // Otherwise, if the LHS is not of the same opcode as the root, return.
+ Instruction *LHSI = dyn_cast<Instruction>(LHS);
+ while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
+ // Should we apply this transform to the RHS?
+ bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
+
+ // If not to the RHS, check to see if we should apply to the LHS...
+ if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
+ cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
+ ShouldApply = true;
+ }
+
+ // If the functor wants to apply the optimization to the RHS of LHSI,
+ // reassociate the expression from ((? op A) op B) to (? op (A op B))
+ if (ShouldApply) {
+ // Now all of the instructions are in the current basic block, go ahead
+ // and perform the reassociation.
+ Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
+
+ // First move the selected RHS to the LHS of the root...
+ Root.setOperand(0, LHSI->getOperand(1));
+
+ // Make what used to be the LHS of the root be the user of the root...
+ Value *ExtraOperand = TmpLHSI->getOperand(1);
+ if (&Root == TmpLHSI) {
+ Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
+ return 0;
+ }
+ Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
+ TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
+ BasicBlock::iterator ARI = &Root; ++ARI;
+ TmpLHSI->moveBefore(ARI); // Move TmpLHSI to after Root
+ ARI = Root;
+
+ // Now propagate the ExtraOperand down the chain of instructions until we
+ // get to LHSI.
+ while (TmpLHSI != LHSI) {
+ Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
+ // Move the instruction to immediately before the chain we are
+ // constructing to avoid breaking dominance properties.
+ NextLHSI->moveBefore(ARI);
+ ARI = NextLHSI;
+
+ Value *NextOp = NextLHSI->getOperand(1);
+ NextLHSI->setOperand(1, ExtraOperand);
+ TmpLHSI = NextLHSI;
+ ExtraOperand = NextOp;
+ }
+
+ // Now that the instructions are reassociated, have the functor perform
+ // the transformation...
+ return F.apply(Root);
+ }
+
+ LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
+ }
+ return 0;
+}
+
+namespace {
+
+// AddRHS - Implements: X + X --> X << 1
+struct AddRHS {
+ Value *RHS;
+ explicit AddRHS(Value *rhs) : RHS(rhs) {}
+ bool shouldApply(Value *LHS) const { return LHS == RHS; }
+ Instruction *apply(BinaryOperator &Add) const {
+ return BinaryOperator::CreateShl(Add.getOperand(0),
+ ConstantInt::get(Add.getType(), 1));
+ }
+};
+
+// AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
+// iff C1&C2 == 0
+struct AddMaskingAnd {
+ Constant *C2;
+ explicit AddMaskingAnd(Constant *c) : C2(c) {}
+ bool shouldApply(Value *LHS) const {
+ ConstantInt *C1;
+ return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
+ ConstantExpr::getAnd(C1, C2)->isNullValue();
+ }
+ Instruction *apply(BinaryOperator &Add) const {
+ return BinaryOperator::CreateOr(Add.getOperand(0), Add.getOperand(1));
+ }
+};
+
+}
+
+static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
+ InstCombiner *IC) {
+ if (CastInst *CI = dyn_cast<CastInst>(&I))
+ return IC->Builder->CreateCast(CI->getOpcode(), SO, I.getType());
+
+ // Figure out if the constant is the left or the right argument.
+ bool ConstIsRHS = isa<Constant>(I.getOperand(1));
+ Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
+
+ if (Constant *SOC = dyn_cast<Constant>(SO)) {
+ if (ConstIsRHS)
+ return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
+ return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
+ }
+
+ Value *Op0 = SO, *Op1 = ConstOperand;
+ if (!ConstIsRHS)
+ std::swap(Op0, Op1);
+
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
+ return IC->Builder->CreateBinOp(BO->getOpcode(), Op0, Op1,
+ SO->getName()+".op");
+ if (ICmpInst *CI = dyn_cast<ICmpInst>(&I))
+ return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
+ SO->getName()+".cmp");
+ if (FCmpInst *CI = dyn_cast<FCmpInst>(&I))
+ return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
+ SO->getName()+".cmp");
+ llvm_unreachable("Unknown binary instruction type!");
+}
+
+// FoldOpIntoSelect - Given an instruction with a select as one operand and a
+// constant as the other operand, try to fold the binary operator into the
+// select arguments. This also works for Cast instructions, which obviously do
+// not have a second operand.
+static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
+ InstCombiner *IC) {
+ // Don't modify shared select instructions
+ if (!SI->hasOneUse()) return 0;
+ Value *TV = SI->getOperand(1);
+ Value *FV = SI->getOperand(2);
+
+ if (isa<Constant>(TV) || isa<Constant>(FV)) {
+ // Bool selects with constant operands can be folded to logical ops.
+ if (SI->getType() == Type::getInt1Ty(*IC->getContext())) return 0;
+
+ Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
+ Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
+
+ return SelectInst::Create(SI->getCondition(), SelectTrueVal,
+ SelectFalseVal);
+ }
+ return 0;
+}
+
+
+/// FoldOpIntoPhi - Given a binary operator, cast instruction, or select which
+/// has a PHI node as operand #0, see if we can fold the instruction into the
+/// PHI (which is only possible if all operands to the PHI are constants).
+///
+/// If AllowAggressive is true, FoldOpIntoPhi will allow certain transforms
+/// that would normally be unprofitable because they strongly encourage jump
+/// threading.
+Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I,
+ bool AllowAggressive) {
+ AllowAggressive = false;
+ PHINode *PN = cast<PHINode>(I.getOperand(0));
+ unsigned NumPHIValues = PN->getNumIncomingValues();
+ if (NumPHIValues == 0 ||
+ // We normally only transform phis with a single use, unless we're trying
+ // hard to make jump threading happen.
+ (!PN->hasOneUse() && !AllowAggressive))
+ return 0;
+
+
+ // Check to see if all of the operands of the PHI are simple constants
+ // (constantint/constantfp/undef). If there is one non-constant value,
+ // remember the BB it is in. If there is more than one or if *it* is a PHI,
+ // bail out. We don't do arbitrary constant expressions here because moving
+ // their computation can be expensive without a cost model.
+ BasicBlock *NonConstBB = 0;
+ for (unsigned i = 0; i != NumPHIValues; ++i)
+ if (!isa<Constant>(PN->getIncomingValue(i)) ||
+ isa<ConstantExpr>(PN->getIncomingValue(i))) {
+ if (NonConstBB) return 0; // More than one non-const value.
+ if (isa<PHINode>(PN->getIncomingValue(i))) return 0; // Itself a phi.
+ NonConstBB = PN->getIncomingBlock(i);
+
+ // If the incoming non-constant value is in I's block, we have an infinite
+ // loop.
+ if (NonConstBB == I.getParent())
+ return 0;
+ }
+
+ // If there is exactly one non-constant value, we can insert a copy of the
+ // operation in that block. However, if this is a critical edge, we would be
+ // inserting the computation one some other paths (e.g. inside a loop). Only
+ // do this if the pred block is unconditionally branching into the phi block.
+ if (NonConstBB != 0 && !AllowAggressive) {
+ BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
+ if (!BI || !BI->isUnconditional()) return 0;
+ }
+
+ // Okay, we can do the transformation: create the new PHI node.
+ PHINode *NewPN = PHINode::Create(I.getType(), "");
+ NewPN->reserveOperandSpace(PN->getNumOperands()/2);
+ InsertNewInstBefore(NewPN, *PN);
+ NewPN->takeName(PN);
+
+ // Next, add all of the operands to the PHI.
+ if (SelectInst *SI = dyn_cast<SelectInst>(&I)) {
+ // We only currently try to fold the condition of a select when it is a phi,
+ // not the true/false values.
+ Value *TrueV = SI->getTrueValue();
+ Value *FalseV = SI->getFalseValue();
+ BasicBlock *PhiTransBB = PN->getParent();
+ for (unsigned i = 0; i != NumPHIValues; ++i) {
+ BasicBlock *ThisBB = PN->getIncomingBlock(i);
+ Value *TrueVInPred = TrueV->DoPHITranslation(PhiTransBB, ThisBB);
+ Value *FalseVInPred = FalseV->DoPHITranslation(PhiTransBB, ThisBB);
+ Value *InV = 0;
+ if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
+ InV = InC->isNullValue() ? FalseVInPred : TrueVInPred;
+ } else {
+ assert(PN->getIncomingBlock(i) == NonConstBB);
+ InV = SelectInst::Create(PN->getIncomingValue(i), TrueVInPred,
+ FalseVInPred,
+ "phitmp", NonConstBB->getTerminator());
+ Worklist.Add(cast<Instruction>(InV));
+ }
+ NewPN->addIncoming(InV, ThisBB);
+ }
+ } else if (I.getNumOperands() == 2) {
+ Constant *C = cast<Constant>(I.getOperand(1));
+ for (unsigned i = 0; i != NumPHIValues; ++i) {
+ Value *InV = 0;
+ if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
+ if (CmpInst *CI = dyn_cast<CmpInst>(&I))
+ InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
+ else
+ InV = ConstantExpr::get(I.getOpcode(), InC, C);
+ } else {
+ assert(PN->getIncomingBlock(i) == NonConstBB);
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
+ InV = BinaryOperator::Create(BO->getOpcode(),
+ PN->getIncomingValue(i), C, "phitmp",
+ NonConstBB->getTerminator());
+ else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
+ InV = CmpInst::Create(CI->getOpcode(),
+ CI->getPredicate(),
+ PN->getIncomingValue(i), C, "phitmp",
+ NonConstBB->getTerminator());
+ else
+ llvm_unreachable("Unknown binop!");
+
+ Worklist.Add(cast<Instruction>(InV));
+ }
+ NewPN->addIncoming(InV, PN->getIncomingBlock(i));
+ }
+ } else {
+ CastInst *CI = cast<CastInst>(&I);
+ const Type *RetTy = CI->getType();
+ for (unsigned i = 0; i != NumPHIValues; ++i) {
+ Value *InV;
+ if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
+ InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy);
+ } else {
+ assert(PN->getIncomingBlock(i) == NonConstBB);
+ InV = CastInst::Create(CI->getOpcode(), PN->getIncomingValue(i),
+ I.getType(), "phitmp",
+ NonConstBB->getTerminator());
+ Worklist.Add(cast<Instruction>(InV));
+ }
+ NewPN->addIncoming(InV, PN->getIncomingBlock(i));
+ }
+ }
+ return ReplaceInstUsesWith(I, NewPN);
+}
+
+
+/// WillNotOverflowSignedAdd - Return true if we can prove that:
+/// (sext (add LHS, RHS)) === (add (sext LHS), (sext RHS))
+/// This basically requires proving that the add in the original type would not
+/// overflow to change the sign bit or have a carry out.
+bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) {
+ // There are different heuristics we can use for this. Here are some simple
+ // ones.
+
+ // Add has the property that adding any two 2's complement numbers can only
+ // have one carry bit which can change a sign. As such, if LHS and RHS each
+ // have at least two sign bits, we know that the addition of the two values
+ // will sign extend fine.
+ if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1)
+ return true;
+
+
+ // If one of the operands only has one non-zero bit, and if the other operand
+ // has a known-zero bit in a more significant place than it (not including the
+ // sign bit) the ripple may go up to and fill the zero, but won't change the
+ // sign. For example, (X & ~4) + 1.
+
+ // TODO: Implement.
+
+ return false;
+}
+
+
+Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+
+ if (Value *V = SimplifyAddInst(LHS, RHS, I.hasNoSignedWrap(),
+ I.hasNoUnsignedWrap(), TD))
+ return ReplaceInstUsesWith(I, V);
+
+
+ if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
+ // X + (signbit) --> X ^ signbit
+ const APInt& Val = CI->getValue();
+ uint32_t BitWidth = Val.getBitWidth();
+ if (Val == APInt::getSignBit(BitWidth))
+ return BinaryOperator::CreateXor(LHS, RHS);
+
+ // See if SimplifyDemandedBits can simplify this. This handles stuff like
+ // (X & 254)+1 -> (X&254)|1
+ if (SimplifyDemandedInstructionBits(I))
+ return &I;
+
+ // zext(bool) + C -> bool ? C + 1 : C
+ if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS))
+ if (ZI->getSrcTy() == Type::getInt1Ty(*Context))
+ return SelectInst::Create(ZI->getOperand(0), AddOne(CI), CI);
+ }
+
+ if (isa<PHINode>(LHS))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+
+ ConstantInt *XorRHS = 0;
+ Value *XorLHS = 0;
+ if (isa<ConstantInt>(RHSC) &&
+ match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
+ uint32_t TySizeBits = I.getType()->getScalarSizeInBits();
+ const APInt& RHSVal = cast<ConstantInt>(RHSC)->getValue();
+
+ uint32_t Size = TySizeBits / 2;
+ APInt C0080Val(APInt(TySizeBits, 1ULL).shl(Size - 1));
+ APInt CFF80Val(-C0080Val);
+ do {
+ if (TySizeBits > Size) {
+ // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
+ // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
+ if ((RHSVal == CFF80Val && XorRHS->getValue() == C0080Val) ||
+ (RHSVal == C0080Val && XorRHS->getValue() == CFF80Val)) {
+ // This is a sign extend if the top bits are known zero.
+ if (!MaskedValueIsZero(XorLHS,
+ APInt::getHighBitsSet(TySizeBits, TySizeBits - Size)))
+ Size = 0; // Not a sign ext, but can't be any others either.
+ break;
+ }
+ }
+ Size >>= 1;
+ C0080Val = APIntOps::lshr(C0080Val, Size);
+ CFF80Val = APIntOps::ashr(CFF80Val, Size);
+ } while (Size >= 1);
+
+ // FIXME: This shouldn't be necessary. When the backends can handle types
+ // with funny bit widths then this switch statement should be removed. It
+ // is just here to get the size of the "middle" type back up to something
+ // that the back ends can handle.
+ const Type *MiddleType = 0;
+ switch (Size) {
+ default: break;
+ case 32: MiddleType = Type::getInt32Ty(*Context); break;
+ case 16: MiddleType = Type::getInt16Ty(*Context); break;
+ case 8: MiddleType = Type::getInt8Ty(*Context); break;
+ }
+ if (MiddleType) {
+ Value *NewTrunc = Builder->CreateTrunc(XorLHS, MiddleType, "sext");
+ return new SExtInst(NewTrunc, I.getType(), I.getName());
+ }
+ }
+ }
+
+ if (I.getType() == Type::getInt1Ty(*Context))
+ return BinaryOperator::CreateXor(LHS, RHS);
+
+ // X + X --> X << 1
+ if (I.getType()->isInteger()) {
+ if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS)))
+ return Result;
+
+ if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
+ if (RHSI->getOpcode() == Instruction::Sub)
+ if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
+ return ReplaceInstUsesWith(I, RHSI->getOperand(0));
+ }
+ if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
+ if (LHSI->getOpcode() == Instruction::Sub)
+ if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
+ return ReplaceInstUsesWith(I, LHSI->getOperand(0));
+ }
+ }
+
+ // -A + B --> B - A
+ // -A + -B --> -(A + B)
+ if (Value *LHSV = dyn_castNegVal(LHS)) {
+ if (LHS->getType()->isIntOrIntVector()) {
+ if (Value *RHSV = dyn_castNegVal(RHS)) {
+ Value *NewAdd = Builder->CreateAdd(LHSV, RHSV, "sum");
+ return BinaryOperator::CreateNeg(NewAdd);
+ }
+ }
+
+ return BinaryOperator::CreateSub(RHS, LHSV);
+ }
+
+ // A + -B --> A - B
+ if (!isa<Constant>(RHS))
+ if (Value *V = dyn_castNegVal(RHS))
+ return BinaryOperator::CreateSub(LHS, V);
+
+
+ ConstantInt *C2;
+ if (Value *X = dyn_castFoldableMul(LHS, C2)) {
+ if (X == RHS) // X*C + X --> X * (C+1)
+ return BinaryOperator::CreateMul(RHS, AddOne(C2));
+
+ // X*C1 + X*C2 --> X * (C1+C2)
+ ConstantInt *C1;
+ if (X == dyn_castFoldableMul(RHS, C1))
+ return BinaryOperator::CreateMul(X, ConstantExpr::getAdd(C1, C2));
+ }
+
+ // X + X*C --> X * (C+1)
+ if (dyn_castFoldableMul(RHS, C2) == LHS)
+ return BinaryOperator::CreateMul(LHS, AddOne(C2));
+
+ // X + ~X --> -1 since ~X = -X-1
+ if (dyn_castNotVal(LHS) == RHS ||
+ dyn_castNotVal(RHS) == LHS)
+ return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+
+ // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
+ if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
+ if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2)))
+ return R;
+
+ // A+B --> A|B iff A and B have no bits set in common.
+ if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
+ APInt Mask = APInt::getAllOnesValue(IT->getBitWidth());
+ APInt LHSKnownOne(IT->getBitWidth(), 0);
+ APInt LHSKnownZero(IT->getBitWidth(), 0);
+ ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
+ if (LHSKnownZero != 0) {
+ APInt RHSKnownOne(IT->getBitWidth(), 0);
+ APInt RHSKnownZero(IT->getBitWidth(), 0);
+ ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
+
+ // No bits in common -> bitwise or.
+ if ((LHSKnownZero|RHSKnownZero).isAllOnesValue())
+ return BinaryOperator::CreateOr(LHS, RHS);
+ }
+ }
+
+ // W*X + Y*Z --> W * (X+Z) iff W == Y
+ if (I.getType()->isIntOrIntVector()) {
+ Value *W, *X, *Y, *Z;
+ if (match(LHS, m_Mul(m_Value(W), m_Value(X))) &&
+ match(RHS, m_Mul(m_Value(Y), m_Value(Z)))) {
+ if (W != Y) {
+ if (W == Z) {
+ std::swap(Y, Z);
+ } else if (Y == X) {
+ std::swap(W, X);
+ } else if (X == Z) {
+ std::swap(Y, Z);
+ std::swap(W, X);
+ }
+ }
+
+ if (W == Y) {
+ Value *NewAdd = Builder->CreateAdd(X, Z, LHS->getName());
+ return BinaryOperator::CreateMul(W, NewAdd);
+ }
+ }
+ }
+
+ if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
+ Value *X = 0;
+ if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
+ return BinaryOperator::CreateSub(SubOne(CRHS), X);
+
+ // (X & FF00) + xx00 -> (X+xx00) & FF00
+ if (LHS->hasOneUse() &&
+ match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
+ Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
+ if (Anded == CRHS) {
+ // See if all bits from the first bit set in the Add RHS up are included
+ // in the mask. First, get the rightmost bit.
+ const APInt& AddRHSV = CRHS->getValue();
+
+ // Form a mask of all bits from the lowest bit added through the top.
+ APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
+
+ // See if the and mask includes all of these bits.
+ APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
+
+ if (AddRHSHighBits == AddRHSHighBitsAnd) {
+ // Okay, the xform is safe. Insert the new add pronto.
+ Value *NewAdd = Builder->CreateAdd(X, CRHS, LHS->getName());
+ return BinaryOperator::CreateAnd(NewAdd, C2);
+ }
+ }
+ }
+
+ // Try to fold constant add into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ }
+
+ // add (select X 0 (sub n A)) A --> select X A n
+ {
+ SelectInst *SI = dyn_cast<SelectInst>(LHS);
+ Value *A = RHS;
+ if (!SI) {
+ SI = dyn_cast<SelectInst>(RHS);
+ A = LHS;
+ }
+ if (SI && SI->hasOneUse()) {
+ Value *TV = SI->getTrueValue();
+ Value *FV = SI->getFalseValue();
+ Value *N;
+
+ // Can we fold the add into the argument of the select?
+ // We check both true and false select arguments for a matching subtract.
+ if (match(FV, m_Zero()) &&
+ match(TV, m_Sub(m_Value(N), m_Specific(A))))
+ // Fold the add into the true select value.
+ return SelectInst::Create(SI->getCondition(), N, A);
+ if (match(TV, m_Zero()) &&
+ match(FV, m_Sub(m_Value(N), m_Specific(A))))
+ // Fold the add into the false select value.
+ return SelectInst::Create(SI->getCondition(), A, N);
+ }
+ }
+
+ // Check for (add (sext x), y), see if we can merge this into an
+ // integer add followed by a sext.
+ if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) {
+ // (add (sext x), cst) --> (sext (add x, cst'))
+ if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
+ Constant *CI =
+ ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
+ if (LHSConv->hasOneUse() &&
+ ConstantExpr::getSExt(CI, I.getType()) == RHSC &&
+ WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
+ // Insert the new, smaller add.
+ Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
+ CI, "addconv");
+ return new SExtInst(NewAdd, I.getType());
+ }
+ }
+
+ // (add (sext x), (sext y)) --> (sext (add int x, y))
+ if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) {
+ // Only do this if x/y have the same type, if at last one of them has a
+ // single use (so we don't increase the number of sexts), and if the
+ // integer add will not overflow.
+ if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
+ (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
+ WillNotOverflowSignedAdd(LHSConv->getOperand(0),
+ RHSConv->getOperand(0))) {
+ // Insert the new integer add.
+ Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
+ RHSConv->getOperand(0), "addconv");
+ return new SExtInst(NewAdd, I.getType());
+ }
+ }
+ }
+
+ return Changed ? &I : 0;
+}
+
+Instruction *InstCombiner::visitFAdd(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+
+ if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
+ // X + 0 --> X
+ if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
+ if (CFP->isExactlyValue(ConstantFP::getNegativeZero
+ (I.getType())->getValueAPF()))
+ return ReplaceInstUsesWith(I, LHS);
+ }
+
+ if (isa<PHINode>(LHS))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+ // -A + B --> B - A
+ // -A + -B --> -(A + B)
+ if (Value *LHSV = dyn_castFNegVal(LHS))
+ return BinaryOperator::CreateFSub(RHS, LHSV);
+
+ // A + -B --> A - B
+ if (!isa<Constant>(RHS))
+ if (Value *V = dyn_castFNegVal(RHS))
+ return BinaryOperator::CreateFSub(LHS, V);
+
+ // Check for X+0.0. Simplify it to X if we know X is not -0.0.
+ if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS))
+ if (CFP->getValueAPF().isPosZero() && CannotBeNegativeZero(LHS))
+ return ReplaceInstUsesWith(I, LHS);
+
+ // Check for (add double (sitofp x), y), see if we can merge this into an
+ // integer add followed by a promotion.
+ if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) {
+ // (add double (sitofp x), fpcst) --> (sitofp (add int x, intcst))
+ // ... if the constant fits in the integer value. This is useful for things
+ // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer
+ // requires a constant pool load, and generally allows the add to be better
+ // instcombined.
+ if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) {
+ Constant *CI =
+ ConstantExpr::getFPToSI(CFP, LHSConv->getOperand(0)->getType());
+ if (LHSConv->hasOneUse() &&
+ ConstantExpr::getSIToFP(CI, I.getType()) == CFP &&
+ WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
+ // Insert the new integer add.
+ Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
+ CI, "addconv");
+ return new SIToFPInst(NewAdd, I.getType());
+ }
+ }
+
+ // (add double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))
+ if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) {
+ // Only do this if x/y have the same type, if at last one of them has a
+ // single use (so we don't increase the number of int->fp conversions),
+ // and if the integer add will not overflow.
+ if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
+ (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
+ WillNotOverflowSignedAdd(LHSConv->getOperand(0),
+ RHSConv->getOperand(0))) {
+ // Insert the new integer add.
+ Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
+ RHSConv->getOperand(0),"addconv");
+ return new SIToFPInst(NewAdd, I.getType());
+ }
+ }
+ }
+
+ return Changed ? &I : 0;
+}
+
+
+/// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
+/// code necessary to compute the offset from the base pointer (without adding
+/// in the base pointer). Return the result as a signed integer of intptr size.
+static Value *EmitGEPOffset(User *GEP, InstCombiner &IC) {
+ TargetData &TD = *IC.getTargetData();
+ gep_type_iterator GTI = gep_type_begin(GEP);
+ const Type *IntPtrTy = TD.getIntPtrType(GEP->getContext());
+ Value *Result = Constant::getNullValue(IntPtrTy);
+
+ // Build a mask for high order bits.
+ unsigned IntPtrWidth = TD.getPointerSizeInBits();
+ uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
+
+ for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
+ ++i, ++GTI) {
+ Value *Op = *i;
+ uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()) & PtrSizeMask;
+ if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
+ if (OpC->isZero()) continue;
+
+ // Handle a struct index, which adds its field offset to the pointer.
+ if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+ Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
+
+ Result = IC.Builder->CreateAdd(Result,
+ ConstantInt::get(IntPtrTy, Size),
+ GEP->getName()+".offs");
+ continue;
+ }
+
+ Constant *Scale = ConstantInt::get(IntPtrTy, Size);
+ Constant *OC =
+ ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
+ Scale = ConstantExpr::getMul(OC, Scale);
+ // Emit an add instruction.
+ Result = IC.Builder->CreateAdd(Result, Scale, GEP->getName()+".offs");
+ continue;
+ }
+ // Convert to correct type.
+ if (Op->getType() != IntPtrTy)
+ Op = IC.Builder->CreateIntCast(Op, IntPtrTy, true, Op->getName()+".c");
+ if (Size != 1) {
+ Constant *Scale = ConstantInt::get(IntPtrTy, Size);
+ // We'll let instcombine(mul) convert this to a shl if possible.
+ Op = IC.Builder->CreateMul(Op, Scale, GEP->getName()+".idx");
+ }
+
+ // Emit an add instruction.
+ Result = IC.Builder->CreateAdd(Op, Result, GEP->getName()+".offs");
+ }
+ return Result;
+}
+
+
+/// EvaluateGEPOffsetExpression - Return a value that can be used to compare
+/// the *offset* implied by a GEP to zero. For example, if we have &A[i], we
+/// want to return 'i' for "icmp ne i, 0". Note that, in general, indices can
+/// be complex, and scales are involved. The above expression would also be
+/// legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32).
+/// This later form is less amenable to optimization though, and we are allowed
+/// to generate the first by knowing that pointer arithmetic doesn't overflow.
+///
+/// If we can't emit an optimized form for this expression, this returns null.
+///
+static Value *EvaluateGEPOffsetExpression(User *GEP, Instruction &I,
+ InstCombiner &IC) {
+ TargetData &TD = *IC.getTargetData();
+ gep_type_iterator GTI = gep_type_begin(GEP);
+
+ // Check to see if this gep only has a single variable index. If so, and if
+ // any constant indices are a multiple of its scale, then we can compute this
+ // in terms of the scale of the variable index. For example, if the GEP
+ // implies an offset of "12 + i*4", then we can codegen this as "3 + i",
+ // because the expression will cross zero at the same point.
+ unsigned i, e = GEP->getNumOperands();
+ int64_t Offset = 0;
+ for (i = 1; i != e; ++i, ++GTI) {
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
+ // Compute the aggregate offset of constant indices.
+ if (CI->isZero()) continue;
+
+ // Handle a struct index, which adds its field offset to the pointer.
+ if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+ Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
+ } else {
+ uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
+ Offset += Size*CI->getSExtValue();
+ }
+ } else {
+ // Found our variable index.
+ break;
+ }
+ }
+
+ // If there are no variable indices, we must have a constant offset, just
+ // evaluate it the general way.
+ if (i == e) return 0;
+
+ Value *VariableIdx = GEP->getOperand(i);
+ // Determine the scale factor of the variable element. For example, this is
+ // 4 if the variable index is into an array of i32.
+ uint64_t VariableScale = TD.getTypeAllocSize(GTI.getIndexedType());
+
+ // Verify that there are no other variable indices. If so, emit the hard way.
+ for (++i, ++GTI; i != e; ++i, ++GTI) {
+ ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
+ if (!CI) return 0;
+
+ // Compute the aggregate offset of constant indices.
+ if (CI->isZero()) continue;
+
+ // Handle a struct index, which adds its field offset to the pointer.
+ if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+ Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
+ } else {
+ uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
+ Offset += Size*CI->getSExtValue();
+ }
+ }
+
+ // Okay, we know we have a single variable index, which must be a
+ // pointer/array/vector index. If there is no offset, life is simple, return
+ // the index.
+ unsigned IntPtrWidth = TD.getPointerSizeInBits();
+ if (Offset == 0) {
+ // Cast to intptrty in case a truncation occurs. If an extension is needed,
+ // we don't need to bother extending: the extension won't affect where the
+ // computation crosses zero.
+ if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth)
+ VariableIdx = new TruncInst(VariableIdx,
+ TD.getIntPtrType(VariableIdx->getContext()),
+ VariableIdx->getName(), &I);
+ return VariableIdx;
+ }
+
+ // Otherwise, there is an index. The computation we will do will be modulo
+ // the pointer size, so get it.
+ uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
+
+ Offset &= PtrSizeMask;
+ VariableScale &= PtrSizeMask;
+
+ // To do this transformation, any constant index must be a multiple of the
+ // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i",
+ // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a
+ // multiple of the variable scale.
+ int64_t NewOffs = Offset / (int64_t)VariableScale;
+ if (Offset != NewOffs*(int64_t)VariableScale)
+ return 0;
+
+ // Okay, we can do this evaluation. Start by converting the index to intptr.
+ const Type *IntPtrTy = TD.getIntPtrType(VariableIdx->getContext());
+ if (VariableIdx->getType() != IntPtrTy)
+ VariableIdx = CastInst::CreateIntegerCast(VariableIdx, IntPtrTy,
+ true /*SExt*/,
+ VariableIdx->getName(), &I);
+ Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
+ return BinaryOperator::CreateAdd(VariableIdx, OffsetVal, "offset", &I);
+}
+
+
+/// Optimize pointer differences into the same array into a size. Consider:
+/// &A[10] - &A[0]: we should compile this to "10". LHS/RHS are the pointer
+/// operands to the ptrtoint instructions for the LHS/RHS of the subtract.
+///
+Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS,
+ const Type *Ty) {
+ assert(TD && "Must have target data info for this");
+
+ // If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize
+ // this.
+ bool Swapped;
+ GetElementPtrInst *GEP = 0;
+ ConstantExpr *CstGEP = 0;
+
+ // TODO: Could also optimize &A[i] - &A[j] -> "i-j", and "&A.foo[i] - &A.foo".
+ // For now we require one side to be the base pointer "A" or a constant
+ // expression derived from it.
+ if (GetElementPtrInst *LHSGEP = dyn_cast<GetElementPtrInst>(LHS)) {
+ // (gep X, ...) - X
+ if (LHSGEP->getOperand(0) == RHS) {
+ GEP = LHSGEP;
+ Swapped = false;
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(RHS)) {
+ // (gep X, ...) - (ce_gep X, ...)
+ if (CE->getOpcode() == Instruction::GetElementPtr &&
+ LHSGEP->getOperand(0) == CE->getOperand(0)) {
+ CstGEP = CE;
+ GEP = LHSGEP;
+ Swapped = false;
+ }
+ }
+ }
+
+ if (GetElementPtrInst *RHSGEP = dyn_cast<GetElementPtrInst>(RHS)) {
+ // X - (gep X, ...)
+ if (RHSGEP->getOperand(0) == LHS) {
+ GEP = RHSGEP;
+ Swapped = true;
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(LHS)) {
+ // (ce_gep X, ...) - (gep X, ...)
+ if (CE->getOpcode() == Instruction::GetElementPtr &&
+ RHSGEP->getOperand(0) == CE->getOperand(0)) {
+ CstGEP = CE;
+ GEP = RHSGEP;
+ Swapped = true;
+ }
+ }
+ }
+
+ if (GEP == 0)
+ return 0;
+
+ // Emit the offset of the GEP and an intptr_t.
+ Value *Result = EmitGEPOffset(GEP, *this);
+
+ // If we had a constant expression GEP on the other side offsetting the
+ // pointer, subtract it from the offset we have.
+ if (CstGEP) {
+ Value *CstOffset = EmitGEPOffset(CstGEP, *this);
+ Result = Builder->CreateSub(Result, CstOffset);
+ }
+
+
+ // If we have p - gep(p, ...) then we have to negate the result.
+ if (Swapped)
+ Result = Builder->CreateNeg(Result, "diff.neg");
+
+ return Builder->CreateIntCast(Result, Ty, true);
+}
+
+
+Instruction *InstCombiner::visitSub(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Op0 == Op1) // sub X, X -> 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ // If this is a 'B = x-(-A)', change to B = x+A. This preserves NSW/NUW.
+ if (Value *V = dyn_castNegVal(Op1)) {
+ BinaryOperator *Res = BinaryOperator::CreateAdd(Op0, V);
+ Res->setHasNoSignedWrap(I.hasNoSignedWrap());
+ Res->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
+ return Res;
+ }
+
+ if (isa<UndefValue>(Op0))
+ return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
+ if (isa<UndefValue>(Op1))
+ return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
+ if (I.getType() == Type::getInt1Ty(*Context))
+ return BinaryOperator::CreateXor(Op0, Op1);
+
+ if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
+ // Replace (-1 - A) with (~A).
+ if (C->isAllOnesValue())
+ return BinaryOperator::CreateNot(Op1);
+
+ // C - ~X == X + (1+C)
+ Value *X = 0;
+ if (match(Op1, m_Not(m_Value(X))))
+ return BinaryOperator::CreateAdd(X, AddOne(C));
+
+ // -(X >>u 31) -> (X >>s 31)
+ // -(X >>s 31) -> (X >>u 31)
+ if (C->isZero()) {
+ if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1)) {
+ if (SI->getOpcode() == Instruction::LShr) {
+ if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
+ // Check to see if we are shifting out everything but the sign bit.
+ if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
+ SI->getType()->getPrimitiveSizeInBits()-1) {
+ // Ok, the transformation is safe. Insert AShr.
+ return BinaryOperator::Create(Instruction::AShr,
+ SI->getOperand(0), CU, SI->getName());
+ }
+ }
+ } else if (SI->getOpcode() == Instruction::AShr) {
+ if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
+ // Check to see if we are shifting out everything but the sign bit.
+ if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
+ SI->getType()->getPrimitiveSizeInBits()-1) {
+ // Ok, the transformation is safe. Insert LShr.
+ return BinaryOperator::CreateLShr(
+ SI->getOperand(0), CU, SI->getName());
+ }
+ }
+ }
+ }
+ }
+
+ // Try to fold constant sub into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+
+ // C - zext(bool) -> bool ? C - 1 : C
+ if (ZExtInst *ZI = dyn_cast<ZExtInst>(Op1))
+ if (ZI->getSrcTy() == Type::getInt1Ty(*Context))
+ return SelectInst::Create(ZI->getOperand(0), SubOne(C), C);
+ }
+
+ if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
+ if (Op1I->getOpcode() == Instruction::Add) {
+ if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
+ return BinaryOperator::CreateNeg(Op1I->getOperand(1),
+ I.getName());
+ else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
+ return BinaryOperator::CreateNeg(Op1I->getOperand(0),
+ I.getName());
+ else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
+ if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
+ // C1-(X+C2) --> (C1-C2)-X
+ return BinaryOperator::CreateSub(
+ ConstantExpr::getSub(CI1, CI2), Op1I->getOperand(0));
+ }
+ }
+
+ if (Op1I->hasOneUse()) {
+ // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
+ // is not used by anyone else...
+ //
+ if (Op1I->getOpcode() == Instruction::Sub) {
+ // Swap the two operands of the subexpr...
+ Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
+ Op1I->setOperand(0, IIOp1);
+ Op1I->setOperand(1, IIOp0);
+
+ // Create the new top level add instruction...
+ return BinaryOperator::CreateAdd(Op0, Op1);
+ }
+
+ // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
+ //
+ if (Op1I->getOpcode() == Instruction::And &&
+ (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
+ Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
+
+ Value *NewNot = Builder->CreateNot(OtherOp, "B.not");
+ return BinaryOperator::CreateAnd(Op0, NewNot);
+ }
+
+ // 0 - (X sdiv C) -> (X sdiv -C)
+ if (Op1I->getOpcode() == Instruction::SDiv)
+ if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
+ if (CSI->isZero())
+ if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
+ return BinaryOperator::CreateSDiv(Op1I->getOperand(0),
+ ConstantExpr::getNeg(DivRHS));
+
+ // X - X*C --> X * (1-C)
+ ConstantInt *C2 = 0;
+ if (dyn_castFoldableMul(Op1I, C2) == Op0) {
+ Constant *CP1 =
+ ConstantExpr::getSub(ConstantInt::get(I.getType(), 1),
+ C2);
+ return BinaryOperator::CreateMul(Op0, CP1);
+ }
+ }
+ }
+
+ if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
+ if (Op0I->getOpcode() == Instruction::Add) {
+ if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
+ return ReplaceInstUsesWith(I, Op0I->getOperand(1));
+ else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
+ return ReplaceInstUsesWith(I, Op0I->getOperand(0));
+ } else if (Op0I->getOpcode() == Instruction::Sub) {
+ if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
+ return BinaryOperator::CreateNeg(Op0I->getOperand(1),
+ I.getName());
+ }
+ }
+
+ ConstantInt *C1;
+ if (Value *X = dyn_castFoldableMul(Op0, C1)) {
+ if (X == Op1) // X*C - X --> X * (C-1)
+ return BinaryOperator::CreateMul(Op1, SubOne(C1));
+
+ ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
+ if (X == dyn_castFoldableMul(Op1, C2))
+ return BinaryOperator::CreateMul(X, ConstantExpr::getSub(C1, C2));
+ }
+
+ // Optimize pointer differences into the same array into a size. Consider:
+ // &A[10] - &A[0]: we should compile this to "10".
+ if (TD) {
+ Value *LHSOp, *RHSOp;
+ if (match(Op0, m_PtrToInt(m_Value(LHSOp))) &&
+ match(Op1, m_PtrToInt(m_Value(RHSOp))))
+ if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
+ return ReplaceInstUsesWith(I, Res);
+
+ // trunc(p)-trunc(q) -> trunc(p-q)
+ if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) &&
+ match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp)))))
+ if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
+ return ReplaceInstUsesWith(I, Res);
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitFSub(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // If this is a 'B = x-(-A)', change to B = x+A...
+ if (Value *V = dyn_castFNegVal(Op1))
+ return BinaryOperator::CreateFAdd(Op0, V);
+
+ if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
+ if (Op1I->getOpcode() == Instruction::FAdd) {
+ if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
+ return BinaryOperator::CreateFNeg(Op1I->getOperand(1),
+ I.getName());
+ else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
+ return BinaryOperator::CreateFNeg(Op1I->getOperand(0),
+ I.getName());
+ }
+ }
+
+ return 0;
+}
+
+/// isSignBitCheck - Given an exploded icmp instruction, return true if the
+/// comparison only checks the sign bit. If it only checks the sign bit, set
+/// TrueIfSigned if the result of the comparison is true when the input value is
+/// signed.
+static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
+ bool &TrueIfSigned) {
+ switch (pred) {
+ case ICmpInst::ICMP_SLT: // True if LHS s< 0
+ TrueIfSigned = true;
+ return RHS->isZero();
+ case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
+ TrueIfSigned = true;
+ return RHS->isAllOnesValue();
+ case ICmpInst::ICMP_SGT: // True if LHS s> -1
+ TrueIfSigned = false;
+ return RHS->isAllOnesValue();
+ case ICmpInst::ICMP_UGT:
+ // True if LHS u> RHS and RHS == high-bit-mask - 1
+ TrueIfSigned = true;
+ return RHS->getValue() ==
+ APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
+ case ICmpInst::ICMP_UGE:
+ // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
+ TrueIfSigned = true;
+ return RHS->getValue().isSignBit();
+ default:
+ return false;
+ }
+}
+
+Instruction *InstCombiner::visitMul(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (isa<UndefValue>(Op1)) // undef * X -> 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ // Simplify mul instructions with a constant RHS.
+ if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1C)) {
+
+ // ((X << C1)*C2) == (X * (C2 << C1))
+ if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
+ if (SI->getOpcode() == Instruction::Shl)
+ if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
+ return BinaryOperator::CreateMul(SI->getOperand(0),
+ ConstantExpr::getShl(CI, ShOp));
+
+ if (CI->isZero())
+ return ReplaceInstUsesWith(I, Op1C); // X * 0 == 0
+ if (CI->equalsInt(1)) // X * 1 == X
+ return ReplaceInstUsesWith(I, Op0);
+ if (CI->isAllOnesValue()) // X * -1 == 0 - X
+ return BinaryOperator::CreateNeg(Op0, I.getName());
+
+ const APInt& Val = cast<ConstantInt>(CI)->getValue();
+ if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
+ return BinaryOperator::CreateShl(Op0,
+ ConstantInt::get(Op0->getType(), Val.logBase2()));
+ }
+ } else if (isa<VectorType>(Op1C->getType())) {
+ if (Op1C->isNullValue())
+ return ReplaceInstUsesWith(I, Op1C);
+
+ if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
+ if (Op1V->isAllOnesValue()) // X * -1 == 0 - X
+ return BinaryOperator::CreateNeg(Op0, I.getName());
+
+ // As above, vector X*splat(1.0) -> X in all defined cases.
+ if (Constant *Splat = Op1V->getSplatValue()) {
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Splat))
+ if (CI->equalsInt(1))
+ return ReplaceInstUsesWith(I, Op0);
+ }
+ }
+ }
+
+ if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
+ if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() &&
+ isa<ConstantInt>(Op0I->getOperand(1)) && isa<ConstantInt>(Op1C)) {
+ // Canonicalize (X+C1)*C2 -> X*C2+C1*C2.
+ Value *Add = Builder->CreateMul(Op0I->getOperand(0), Op1C, "tmp");
+ Value *C1C2 = Builder->CreateMul(Op1C, Op0I->getOperand(1));
+ return BinaryOperator::CreateAdd(Add, C1C2);
+
+ }
+
+ // Try to fold constant mul into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+ if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
+ if (Value *Op1v = dyn_castNegVal(Op1))
+ return BinaryOperator::CreateMul(Op0v, Op1v);
+
+ // (X / Y) * Y = X - (X % Y)
+ // (X / Y) * -Y = (X % Y) - X
+ {
+ Value *Op1C = Op1;
+ BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0);
+ if (!BO ||
+ (BO->getOpcode() != Instruction::UDiv &&
+ BO->getOpcode() != Instruction::SDiv)) {
+ Op1C = Op0;
+ BO = dyn_cast<BinaryOperator>(Op1);
+ }
+ Value *Neg = dyn_castNegVal(Op1C);
+ if (BO && BO->hasOneUse() &&
+ (BO->getOperand(1) == Op1C || BO->getOperand(1) == Neg) &&
+ (BO->getOpcode() == Instruction::UDiv ||
+ BO->getOpcode() == Instruction::SDiv)) {
+ Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1);
+
+ // If the division is exact, X % Y is zero.
+ if (SDivOperator *SDiv = dyn_cast<SDivOperator>(BO))
+ if (SDiv->isExact()) {
+ if (Op1BO == Op1C)
+ return ReplaceInstUsesWith(I, Op0BO);
+ return BinaryOperator::CreateNeg(Op0BO);
+ }
+
+ Value *Rem;
+ if (BO->getOpcode() == Instruction::UDiv)
+ Rem = Builder->CreateURem(Op0BO, Op1BO);
+ else
+ Rem = Builder->CreateSRem(Op0BO, Op1BO);
+ Rem->takeName(BO);
+
+ if (Op1BO == Op1C)
+ return BinaryOperator::CreateSub(Op0BO, Rem);
+ return BinaryOperator::CreateSub(Rem, Op0BO);
+ }
+ }
+
+ /// i1 mul -> i1 and.
+ if (I.getType() == Type::getInt1Ty(*Context))
+ return BinaryOperator::CreateAnd(Op0, Op1);
+
+ // X*(1 << Y) --> X << Y
+ // (1 << Y)*X --> X << Y
+ {
+ Value *Y;
+ if (match(Op0, m_Shl(m_One(), m_Value(Y))))
+ return BinaryOperator::CreateShl(Op1, Y);
+ if (match(Op1, m_Shl(m_One(), m_Value(Y))))
+ return BinaryOperator::CreateShl(Op0, Y);
+ }
+
+ // If one of the operands of the multiply is a cast from a boolean value, then
+ // we know the bool is either zero or one, so this is a 'masking' multiply.
+ // X * Y (where Y is 0 or 1) -> X & (0-Y)
+ if (!isa<VectorType>(I.getType())) {
+ // -2 is "-1 << 1" so it is all bits set except the low one.
+ APInt Negative2(I.getType()->getPrimitiveSizeInBits(), (uint64_t)-2, true);
+
+ Value *BoolCast = 0, *OtherOp = 0;
+ if (MaskedValueIsZero(Op0, Negative2))
+ BoolCast = Op0, OtherOp = Op1;
+ else if (MaskedValueIsZero(Op1, Negative2))
+ BoolCast = Op1, OtherOp = Op0;
+
+ if (BoolCast) {
+ Value *V = Builder->CreateSub(Constant::getNullValue(I.getType()),
+ BoolCast, "tmp");
+ return BinaryOperator::CreateAnd(V, OtherOp);
+ }
+ }
+
+ return Changed ? &I : 0;
+}
+
+Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // Simplify mul instructions with a constant RHS...
+ if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
+ if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1C)) {
+ // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
+ // ANSI says we can drop signals, so we can do this anyway." (from GCC)
+ if (Op1F->isExactlyValue(1.0))
+ return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
+ } else if (isa<VectorType>(Op1C->getType())) {
+ if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
+ // As above, vector X*splat(1.0) -> X in all defined cases.
+ if (Constant *Splat = Op1V->getSplatValue()) {
+ if (ConstantFP *F = dyn_cast<ConstantFP>(Splat))
+ if (F->isExactlyValue(1.0))
+ return ReplaceInstUsesWith(I, Op0);
+ }
+ }
+ }
+
+ // Try to fold constant mul into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+ if (Value *Op0v = dyn_castFNegVal(Op0)) // -X * -Y = X*Y
+ if (Value *Op1v = dyn_castFNegVal(Op1))
+ return BinaryOperator::CreateFMul(Op0v, Op1v);
+
+ return Changed ? &I : 0;
+}
+
+/// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select
+/// instruction.
+bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
+ SelectInst *SI = cast<SelectInst>(I.getOperand(1));
+
+ // div/rem X, (Cond ? 0 : Y) -> div/rem X, Y
+ int NonNullOperand = -1;
+ if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
+ if (ST->isNullValue())
+ NonNullOperand = 2;
+ // div/rem X, (Cond ? Y : 0) -> div/rem X, Y
+ if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
+ if (ST->isNullValue())
+ NonNullOperand = 1;
+
+ if (NonNullOperand == -1)
+ return false;
+
+ Value *SelectCond = SI->getOperand(0);
+
+ // Change the div/rem to use 'Y' instead of the select.
+ I.setOperand(1, SI->getOperand(NonNullOperand));
+
+ // Okay, we know we replace the operand of the div/rem with 'Y' with no
+ // problem. However, the select, or the condition of the select may have
+ // multiple uses. Based on our knowledge that the operand must be non-zero,
+ // propagate the known value for the select into other uses of it, and
+ // propagate a known value of the condition into its other users.
+
+ // If the select and condition only have a single use, don't bother with this,
+ // early exit.
+ if (SI->use_empty() && SelectCond->hasOneUse())
+ return true;
+
+ // Scan the current block backward, looking for other uses of SI.
+ BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin();
+
+ while (BBI != BBFront) {
+ --BBI;
+ // If we found a call to a function, we can't assume it will return, so
+ // information from below it cannot be propagated above it.
+ if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
+ break;
+
+ // Replace uses of the select or its condition with the known values.
+ for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end();
+ I != E; ++I) {
+ if (*I == SI) {
+ *I = SI->getOperand(NonNullOperand);
+ Worklist.Add(BBI);
+ } else if (*I == SelectCond) {
+ *I = NonNullOperand == 1 ? ConstantInt::getTrue(*Context) :
+ ConstantInt::getFalse(*Context);
+ Worklist.Add(BBI);
+ }
+ }
+
+ // If we past the instruction, quit looking for it.
+ if (&*BBI == SI)
+ SI = 0;
+ if (&*BBI == SelectCond)
+ SelectCond = 0;
+
+ // If we ran out of things to eliminate, break out of the loop.
+ if (SelectCond == 0 && SI == 0)
+ break;
+
+ }
+ return true;
+}
+
+
+/// This function implements the transforms on div instructions that work
+/// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is
+/// used by the visitors to those instructions.
+/// @brief Transforms common to all three div instructions
+Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // undef / X -> 0 for integer.
+ // undef / X -> undef for FP (the undef could be a snan).
+ if (isa<UndefValue>(Op0)) {
+ if (Op0->getType()->isFPOrFPVector())
+ return ReplaceInstUsesWith(I, Op0);
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ }
+
+ // X / undef -> undef
+ if (isa<UndefValue>(Op1))
+ return ReplaceInstUsesWith(I, Op1);
+
+ return 0;
+}
+
+/// This function implements the transforms common to both integer division
+/// instructions (udiv and sdiv). It is called by the visitors to those integer
+/// division instructions.
+/// @brief Common integer divide transforms
+Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // (sdiv X, X) --> 1 (udiv X, X) --> 1
+ if (Op0 == Op1) {
+ if (const VectorType *Ty = dyn_cast<VectorType>(I.getType())) {
+ Constant *CI = ConstantInt::get(Ty->getElementType(), 1);
+ std::vector<Constant*> Elts(Ty->getNumElements(), CI);
+ return ReplaceInstUsesWith(I, ConstantVector::get(Elts));
+ }
+
+ Constant *CI = ConstantInt::get(I.getType(), 1);
+ return ReplaceInstUsesWith(I, CI);
+ }
+
+ if (Instruction *Common = commonDivTransforms(I))
+ return Common;
+
+ // Handle cases involving: [su]div X, (select Cond, Y, Z)
+ // This does not apply for fdiv.
+ if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
+ return &I;
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+ // div X, 1 == X
+ if (RHS->equalsInt(1))
+ return ReplaceInstUsesWith(I, Op0);
+
+ // (X / C1) / C2 -> X / (C1*C2)
+ if (Instruction *LHS = dyn_cast<Instruction>(Op0))
+ if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
+ if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
+ if (MultiplyOverflows(RHS, LHSRHS,
+ I.getOpcode()==Instruction::SDiv))
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ else
+ return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
+ ConstantExpr::getMul(RHS, LHSRHS));
+ }
+
+ if (!RHS->isZero()) { // avoid X udiv 0
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+ }
+
+ // 0 / X == 0, we don't need to preserve faults!
+ if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
+ if (LHS->equalsInt(0))
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ // It can't be division by zero, hence it must be division by one.
+ if (I.getType() == Type::getInt1Ty(*Context))
+ return ReplaceInstUsesWith(I, Op0);
+
+ if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) {
+ if (ConstantInt *X = cast_or_null<ConstantInt>(Op1V->getSplatValue()))
+ // div X, 1 == X
+ if (X->isOne())
+ return ReplaceInstUsesWith(I, Op0);
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // Handle the integer div common cases
+ if (Instruction *Common = commonIDivTransforms(I))
+ return Common;
+
+ if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
+ // X udiv C^2 -> X >> C
+ // Check to see if this is an unsigned division with an exact power of 2,
+ // if so, convert to a right shift.
+ if (C->getValue().isPowerOf2()) // 0 not included in isPowerOf2
+ return BinaryOperator::CreateLShr(Op0,
+ ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
+
+ // X udiv C, where C >= signbit
+ if (C->getValue().isNegative()) {
+ Value *IC = Builder->CreateICmpULT( Op0, C);
+ return SelectInst::Create(IC, Constant::getNullValue(I.getType()),
+ ConstantInt::get(I.getType(), 1));
+ }
+ }
+
+ // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
+ if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) {
+ if (RHSI->getOpcode() == Instruction::Shl &&
+ isa<ConstantInt>(RHSI->getOperand(0))) {
+ const APInt& C1 = cast<ConstantInt>(RHSI->getOperand(0))->getValue();
+ if (C1.isPowerOf2()) {
+ Value *N = RHSI->getOperand(1);
+ const Type *NTy = N->getType();
+ if (uint32_t C2 = C1.logBase2())
+ N = Builder->CreateAdd(N, ConstantInt::get(NTy, C2), "tmp");
+ return BinaryOperator::CreateLShr(Op0, N);
+ }
+ }
+ }
+
+ // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
+ // where C1&C2 are powers of two.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
+ if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
+ if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
+ const APInt &TVA = STO->getValue(), &FVA = SFO->getValue();
+ if (TVA.isPowerOf2() && FVA.isPowerOf2()) {
+ // Compute the shift amounts
+ uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2();
+ // Construct the "on true" case of the select
+ Constant *TC = ConstantInt::get(Op0->getType(), TSA);
+ Value *TSI = Builder->CreateLShr(Op0, TC, SI->getName()+".t");
+
+ // Construct the "on false" case of the select
+ Constant *FC = ConstantInt::get(Op0->getType(), FSA);
+ Value *FSI = Builder->CreateLShr(Op0, FC, SI->getName()+".f");
+
+ // construct the select instruction and return it.
+ return SelectInst::Create(SI->getOperand(0), TSI, FSI, SI->getName());
+ }
+ }
+ return 0;
+}
+
+Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // Handle the integer div common cases
+ if (Instruction *Common = commonIDivTransforms(I))
+ return Common;
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+ // sdiv X, -1 == -X
+ if (RHS->isAllOnesValue())
+ return BinaryOperator::CreateNeg(Op0);
+
+ // sdiv X, C --> ashr X, log2(C)
+ if (cast<SDivOperator>(&I)->isExact() &&
+ RHS->getValue().isNonNegative() &&
+ RHS->getValue().isPowerOf2()) {
+ Value *ShAmt = llvm::ConstantInt::get(RHS->getType(),
+ RHS->getValue().exactLogBase2());
+ return BinaryOperator::CreateAShr(Op0, ShAmt, I.getName());
+ }
+
+ // -X/C --> X/-C provided the negation doesn't overflow.
+ if (SubOperator *Sub = dyn_cast<SubOperator>(Op0))
+ if (isa<Constant>(Sub->getOperand(0)) &&
+ cast<Constant>(Sub->getOperand(0))->isNullValue() &&
+ Sub->hasNoSignedWrap())
+ return BinaryOperator::CreateSDiv(Sub->getOperand(1),
+ ConstantExpr::getNeg(RHS));
+ }
+
+ // If the sign bits of both operands are zero (i.e. we can prove they are
+ // unsigned inputs), turn this into a udiv.
+ if (I.getType()->isInteger()) {
+ APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
+ if (MaskedValueIsZero(Op0, Mask)) {
+ if (MaskedValueIsZero(Op1, Mask)) {
+ // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
+ return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
+ }
+ ConstantInt *ShiftedInt;
+ if (match(Op1, m_Shl(m_ConstantInt(ShiftedInt), m_Value())) &&
+ ShiftedInt->getValue().isPowerOf2()) {
+ // X sdiv (1 << Y) -> X udiv (1 << Y) ( -> X u>> Y)
+ // Safe because the only negative value (1 << Y) can take on is
+ // INT_MIN, and X sdiv INT_MIN == X udiv INT_MIN == 0 if X doesn't have
+ // the sign bit set.
+ return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
+ }
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
+ return commonDivTransforms(I);
+}
+
+/// This function implements the transforms on rem instructions that work
+/// regardless of the kind of rem instruction it is (urem, srem, or frem). It
+/// is used by the visitors to those instructions.
+/// @brief Transforms common to all three rem instructions
+Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (isa<UndefValue>(Op0)) { // undef % X -> 0
+ if (I.getType()->isFPOrFPVector())
+ return ReplaceInstUsesWith(I, Op0); // X % undef -> undef (could be SNaN)
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ }
+ if (isa<UndefValue>(Op1))
+ return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
+
+ // Handle cases involving: rem X, (select Cond, Y, Z)
+ if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
+ return &I;
+
+ return 0;
+}
+
+/// This function implements the transforms common to both integer remainder
+/// instructions (urem and srem). It is called by the visitors to those integer
+/// remainder instructions.
+/// @brief Common integer remainder transforms
+Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Instruction *common = commonRemTransforms(I))
+ return common;
+
+ // 0 % X == 0 for integer, we don't need to preserve faults!
+ if (Constant *LHS = dyn_cast<Constant>(Op0))
+ if (LHS->isNullValue())
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+ // X % 0 == undef, we don't need to preserve faults!
+ if (RHS->equalsInt(0))
+ return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
+
+ if (RHS->equalsInt(1)) // X % 1 == 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ } else if (isa<PHINode>(Op0I)) {
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+ // See if we can fold away this rem instruction.
+ if (SimplifyDemandedInstructionBits(I))
+ return &I;
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitURem(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Instruction *common = commonIRemTransforms(I))
+ return common;
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+ // X urem C^2 -> X and C
+ // Check to see if this is an unsigned remainder with an exact power of 2,
+ // if so, convert to a bitwise and.
+ if (ConstantInt *C = dyn_cast<ConstantInt>(RHS))
+ if (C->getValue().isPowerOf2())
+ return BinaryOperator::CreateAnd(Op0, SubOne(C));
+ }
+
+ if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
+ // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
+ if (RHSI->getOpcode() == Instruction::Shl &&
+ isa<ConstantInt>(RHSI->getOperand(0))) {
+ if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) {
+ Constant *N1 = Constant::getAllOnesValue(I.getType());
+ Value *Add = Builder->CreateAdd(RHSI, N1, "tmp");
+ return BinaryOperator::CreateAnd(Op0, Add);
+ }
+ }
+ }
+
+ // urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2)
+ // where C1&C2 are powers of two.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
+ if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
+ if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
+ // STO == 0 and SFO == 0 handled above.
+ if ((STO->getValue().isPowerOf2()) &&
+ (SFO->getValue().isPowerOf2())) {
+ Value *TrueAnd = Builder->CreateAnd(Op0, SubOne(STO),
+ SI->getName()+".t");
+ Value *FalseAnd = Builder->CreateAnd(Op0, SubOne(SFO),
+ SI->getName()+".f");
+ return SelectInst::Create(SI->getOperand(0), TrueAnd, FalseAnd);
+ }
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // Handle the integer rem common cases
+ if (Instruction *Common = commonIRemTransforms(I))
+ return Common;
+
+ if (Value *RHSNeg = dyn_castNegVal(Op1))
+ if (!isa<Constant>(RHSNeg) ||
+ (isa<ConstantInt>(RHSNeg) &&
+ cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive())) {
+ // X % -Y -> X % Y
+ Worklist.AddValue(I.getOperand(1));
+ I.setOperand(1, RHSNeg);
+ return &I;
+ }
+
+ // If the sign bits of both operands are zero (i.e. we can prove they are
+ // unsigned inputs), turn this into a urem.
+ if (I.getType()->isInteger()) {
+ APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
+ if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
+ // X srem Y -> X urem Y, iff X and Y don't have sign bit set
+ return BinaryOperator::CreateURem(Op0, Op1, I.getName());
+ }
+ }
+
+ // If it's a constant vector, flip any negative values positive.
+ if (ConstantVector *RHSV = dyn_cast<ConstantVector>(Op1)) {
+ unsigned VWidth = RHSV->getNumOperands();
+
+ bool hasNegative = false;
+ for (unsigned i = 0; !hasNegative && i != VWidth; ++i)
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i)))
+ if (RHS->getValue().isNegative())
+ hasNegative = true;
+
+ if (hasNegative) {
+ std::vector<Constant *> Elts(VWidth);
+ for (unsigned i = 0; i != VWidth; ++i) {
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i))) {
+ if (RHS->getValue().isNegative())
+ Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
+ else
+ Elts[i] = RHS;
+ }
+ }
+
+ Constant *NewRHSV = ConstantVector::get(Elts);
+ if (NewRHSV != RHSV) {
+ Worklist.AddValue(I.getOperand(1));
+ I.setOperand(1, NewRHSV);
+ return &I;
+ }
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
+ return commonRemTransforms(I);
+}
+
+// isOneBitSet - Return true if there is exactly one bit set in the specified
+// constant.
+static bool isOneBitSet(const ConstantInt *CI) {
+ return CI->getValue().isPowerOf2();
+}
+
+// isHighOnes - Return true if the constant is of the form 1+0+.
+// This is the same as lowones(~X).
+static bool isHighOnes(const ConstantInt *CI) {
+ return (~CI->getValue() + 1).isPowerOf2();
+}
+
+/// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
+/// are carefully arranged to allow folding of expressions such as:
+///
+/// (A < B) | (A > B) --> (A != B)
+///
+/// Note that this is only valid if the first and second predicates have the
+/// same sign. Is illegal to do: (A u< B) | (A s> B)
+///
+/// Three bits are used to represent the condition, as follows:
+/// 0 A > B
+/// 1 A == B
+/// 2 A < B
+///
+/// <=> Value Definition
+/// 000 0 Always false
+/// 001 1 A > B
+/// 010 2 A == B
+/// 011 3 A >= B
+/// 100 4 A < B
+/// 101 5 A != B
+/// 110 6 A <= B
+/// 111 7 Always true
+///
+static unsigned getICmpCode(const ICmpInst *ICI) {
+ switch (ICI->getPredicate()) {
+ // False -> 0
+ case ICmpInst::ICMP_UGT: return 1; // 001
+ case ICmpInst::ICMP_SGT: return 1; // 001
+ case ICmpInst::ICMP_EQ: return 2; // 010
+ case ICmpInst::ICMP_UGE: return 3; // 011
+ case ICmpInst::ICMP_SGE: return 3; // 011
+ case ICmpInst::ICMP_ULT: return 4; // 100
+ case ICmpInst::ICMP_SLT: return 4; // 100
+ case ICmpInst::ICMP_NE: return 5; // 101
+ case ICmpInst::ICMP_ULE: return 6; // 110
+ case ICmpInst::ICMP_SLE: return 6; // 110
+ // True -> 7
+ default:
+ llvm_unreachable("Invalid ICmp predicate!");
+ return 0;
+ }
+}
+
+/// getFCmpCode - Similar to getICmpCode but for FCmpInst. This encodes a fcmp
+/// predicate into a three bit mask. It also returns whether it is an ordered
+/// predicate by reference.
+static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) {
+ isOrdered = false;
+ switch (CC) {
+ case FCmpInst::FCMP_ORD: isOrdered = true; return 0; // 000
+ case FCmpInst::FCMP_UNO: return 0; // 000
+ case FCmpInst::FCMP_OGT: isOrdered = true; return 1; // 001
+ case FCmpInst::FCMP_UGT: return 1; // 001
+ case FCmpInst::FCMP_OEQ: isOrdered = true; return 2; // 010
+ case FCmpInst::FCMP_UEQ: return 2; // 010
+ case FCmpInst::FCMP_OGE: isOrdered = true; return 3; // 011
+ case FCmpInst::FCMP_UGE: return 3; // 011
+ case FCmpInst::FCMP_OLT: isOrdered = true; return 4; // 100
+ case FCmpInst::FCMP_ULT: return 4; // 100
+ case FCmpInst::FCMP_ONE: isOrdered = true; return 5; // 101
+ case FCmpInst::FCMP_UNE: return 5; // 101
+ case FCmpInst::FCMP_OLE: isOrdered = true; return 6; // 110
+ case FCmpInst::FCMP_ULE: return 6; // 110
+ // True -> 7
+ default:
+ // Not expecting FCMP_FALSE and FCMP_TRUE;
+ llvm_unreachable("Unexpected FCmp predicate!");
+ return 0;
+ }
+}
+
+/// getICmpValue - This is the complement of getICmpCode, which turns an
+/// opcode and two operands into either a constant true or false, or a brand
+/// new ICmp instruction. The sign is passed in to determine which kind
+/// of predicate to use in the new icmp instruction.
+static Value *getICmpValue(bool sign, unsigned code, Value *LHS, Value *RHS,
+ LLVMContext *Context) {
+ switch (code) {
+ default: llvm_unreachable("Illegal ICmp code!");
+ case 0: return ConstantInt::getFalse(*Context);
+ case 1:
+ if (sign)
+ return new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS);
+ else
+ return new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS);
+ case 2: return new ICmpInst(ICmpInst::ICMP_EQ, LHS, RHS);
+ case 3:
+ if (sign)
+ return new ICmpInst(ICmpInst::ICMP_SGE, LHS, RHS);
+ else
+ return new ICmpInst(ICmpInst::ICMP_UGE, LHS, RHS);
+ case 4:
+ if (sign)
+ return new ICmpInst(ICmpInst::ICMP_SLT, LHS, RHS);
+ else
+ return new ICmpInst(ICmpInst::ICMP_ULT, LHS, RHS);
+ case 5: return new ICmpInst(ICmpInst::ICMP_NE, LHS, RHS);
+ case 6:
+ if (sign)
+ return new ICmpInst(ICmpInst::ICMP_SLE, LHS, RHS);
+ else
+ return new ICmpInst(ICmpInst::ICMP_ULE, LHS, RHS);
+ case 7: return ConstantInt::getTrue(*Context);
+ }
+}
+
+/// getFCmpValue - This is the complement of getFCmpCode, which turns an
+/// opcode and two operands into either a FCmp instruction. isordered is passed
+/// in to determine which kind of predicate to use in the new fcmp instruction.
+static Value *getFCmpValue(bool isordered, unsigned code,
+ Value *LHS, Value *RHS, LLVMContext *Context) {
+ switch (code) {
+ default: llvm_unreachable("Illegal FCmp code!");
+ case 0:
+ if (isordered)
+ return new FCmpInst(FCmpInst::FCMP_ORD, LHS, RHS);
+ else
+ return new FCmpInst(FCmpInst::FCMP_UNO, LHS, RHS);
+ case 1:
+ if (isordered)
+ return new FCmpInst(FCmpInst::FCMP_OGT, LHS, RHS);
+ else
+ return new FCmpInst(FCmpInst::FCMP_UGT, LHS, RHS);
+ case 2:
+ if (isordered)
+ return new FCmpInst(FCmpInst::FCMP_OEQ, LHS, RHS);
+ else
+ return new FCmpInst(FCmpInst::FCMP_UEQ, LHS, RHS);
+ case 3:
+ if (isordered)
+ return new FCmpInst(FCmpInst::FCMP_OGE, LHS, RHS);
+ else
+ return new FCmpInst(FCmpInst::FCMP_UGE, LHS, RHS);
+ case 4:
+ if (isordered)
+ return new FCmpInst(FCmpInst::FCMP_OLT, LHS, RHS);
+ else
+ return new FCmpInst(FCmpInst::FCMP_ULT, LHS, RHS);
+ case 5:
+ if (isordered)
+ return new FCmpInst(FCmpInst::FCMP_ONE, LHS, RHS);
+ else
+ return new FCmpInst(FCmpInst::FCMP_UNE, LHS, RHS);
+ case 6:
+ if (isordered)
+ return new FCmpInst(FCmpInst::FCMP_OLE, LHS, RHS);
+ else
+ return new FCmpInst(FCmpInst::FCMP_ULE, LHS, RHS);
+ case 7: return ConstantInt::getTrue(*Context);
+ }
+}
+
+/// PredicatesFoldable - Return true if both predicates match sign or if at
+/// least one of them is an equality comparison (which is signless).
+static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
+ return (CmpInst::isSigned(p1) == CmpInst::isSigned(p2)) ||
+ (CmpInst::isSigned(p1) && ICmpInst::isEquality(p2)) ||
+ (CmpInst::isSigned(p2) && ICmpInst::isEquality(p1));
+}
+
+namespace {
+// FoldICmpLogical - Implements (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
+struct FoldICmpLogical {
+ InstCombiner &IC;
+ Value *LHS, *RHS;
+ ICmpInst::Predicate pred;
+ FoldICmpLogical(InstCombiner &ic, ICmpInst *ICI)
+ : IC(ic), LHS(ICI->getOperand(0)), RHS(ICI->getOperand(1)),
+ pred(ICI->getPredicate()) {}
+ bool shouldApply(Value *V) const {
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(V))
+ if (PredicatesFoldable(pred, ICI->getPredicate()))
+ return ((ICI->getOperand(0) == LHS && ICI->getOperand(1) == RHS) ||
+ (ICI->getOperand(0) == RHS && ICI->getOperand(1) == LHS));
+ return false;
+ }
+ Instruction *apply(Instruction &Log) const {
+ ICmpInst *ICI = cast<ICmpInst>(Log.getOperand(0));
+ if (ICI->getOperand(0) != LHS) {
+ assert(ICI->getOperand(1) == LHS);
+ ICI->swapOperands(); // Swap the LHS and RHS of the ICmp
+ }
+
+ ICmpInst *RHSICI = cast<ICmpInst>(Log.getOperand(1));
+ unsigned LHSCode = getICmpCode(ICI);
+ unsigned RHSCode = getICmpCode(RHSICI);
+ unsigned Code;
+ switch (Log.getOpcode()) {
+ case Instruction::And: Code = LHSCode & RHSCode; break;
+ case Instruction::Or: Code = LHSCode | RHSCode; break;
+ case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
+ default: llvm_unreachable("Illegal logical opcode!"); return 0;
+ }
+
+ bool isSigned = RHSICI->isSigned() || ICI->isSigned();
+ Value *RV = getICmpValue(isSigned, Code, LHS, RHS, IC.getContext());
+ if (Instruction *I = dyn_cast<Instruction>(RV))
+ return I;
+ // Otherwise, it's a constant boolean value...
+ return IC.ReplaceInstUsesWith(Log, RV);
+ }
+};
+} // end anonymous namespace
+
+// OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
+// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
+// guaranteed to be a binary operator.
+Instruction *InstCombiner::OptAndOp(Instruction *Op,
+ ConstantInt *OpRHS,
+ ConstantInt *AndRHS,
+ BinaryOperator &TheAnd) {
+ Value *X = Op->getOperand(0);
+ Constant *Together = 0;
+ if (!Op->isShift())
+ Together = ConstantExpr::getAnd(AndRHS, OpRHS);
+
+ switch (Op->getOpcode()) {
+ case Instruction::Xor:
+ if (Op->hasOneUse()) {
+ // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
+ Value *And = Builder->CreateAnd(X, AndRHS);
+ And->takeName(Op);
+ return BinaryOperator::CreateXor(And, Together);
+ }
+ break;
+ case Instruction::Or:
+ if (Together == AndRHS) // (X | C) & C --> C
+ return ReplaceInstUsesWith(TheAnd, AndRHS);
+
+ if (Op->hasOneUse() && Together != OpRHS) {
+ // (X | C1) & C2 --> (X | (C1&C2)) & C2
+ Value *Or = Builder->CreateOr(X, Together);
+ Or->takeName(Op);
+ return BinaryOperator::CreateAnd(Or, AndRHS);
+ }
+ break;
+ case Instruction::Add:
+ if (Op->hasOneUse()) {
+ // Adding a one to a single bit bit-field should be turned into an XOR
+ // of the bit. First thing to check is to see if this AND is with a
+ // single bit constant.
+ const APInt& AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
+
+ // If there is only one bit set...
+ if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
+ // Ok, at this point, we know that we are masking the result of the
+ // ADD down to exactly one bit. If the constant we are adding has
+ // no bits set below this bit, then we can eliminate the ADD.
+ const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue();
+
+ // Check to see if any bits below the one bit set in AndRHSV are set.
+ if ((AddRHS & (AndRHSV-1)) == 0) {
+ // If not, the only thing that can effect the output of the AND is
+ // the bit specified by AndRHSV. If that bit is set, the effect of
+ // the XOR is to toggle the bit. If it is clear, then the ADD has
+ // no effect.
+ if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
+ TheAnd.setOperand(0, X);
+ return &TheAnd;
+ } else {
+ // Pull the XOR out of the AND.
+ Value *NewAnd = Builder->CreateAnd(X, AndRHS);
+ NewAnd->takeName(Op);
+ return BinaryOperator::CreateXor(NewAnd, AndRHS);
+ }
+ }
+ }
+ }
+ break;
+
+ case Instruction::Shl: {
+ // We know that the AND will not produce any of the bits shifted in, so if
+ // the anded constant includes them, clear them now!
+ //
+ uint32_t BitWidth = AndRHS->getType()->getBitWidth();
+ uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
+ APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
+ ConstantInt *CI = ConstantInt::get(*Context, AndRHS->getValue() & ShlMask);
+
+ if (CI->getValue() == ShlMask) {
+ // Masking out bits that the shift already masks
+ return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
+ } else if (CI != AndRHS) { // Reducing bits set in and.
+ TheAnd.setOperand(1, CI);
+ return &TheAnd;
+ }
+ break;
+ }
+ case Instruction::LShr:
+ {
+ // We know that the AND will not produce any of the bits shifted in, so if
+ // the anded constant includes them, clear them now! This only applies to
+ // unsigned shifts, because a signed shr may bring in set bits!
+ //
+ uint32_t BitWidth = AndRHS->getType()->getBitWidth();
+ uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
+ APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
+ ConstantInt *CI = ConstantInt::get(*Context, AndRHS->getValue() & ShrMask);
+
+ if (CI->getValue() == ShrMask) {
+ // Masking out bits that the shift already masks.
+ return ReplaceInstUsesWith(TheAnd, Op);
+ } else if (CI != AndRHS) {
+ TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
+ return &TheAnd;
+ }
+ break;
+ }
+ case Instruction::AShr:
+ // Signed shr.
+ // See if this is shifting in some sign extension, then masking it out
+ // with an and.
+ if (Op->hasOneUse()) {
+ uint32_t BitWidth = AndRHS->getType()->getBitWidth();
+ uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
+ APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
+ Constant *C = ConstantInt::get(*Context, AndRHS->getValue() & ShrMask);
+ if (C == AndRHS) { // Masking out bits shifted in.
+ // (Val ashr C1) & C2 -> (Val lshr C1) & C2
+ // Make the argument unsigned.
+ Value *ShVal = Op->getOperand(0);
+ ShVal = Builder->CreateLShr(ShVal, OpRHS, Op->getName());
+ return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName());
+ }
+ }
+ break;
+ }
+ return 0;
+}
+
+
+/// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
+/// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
+/// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates
+/// whether to treat the V, Lo and HI as signed or not. IB is the location to
+/// insert new instructions.
+Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
+ bool isSigned, bool Inside,
+ Instruction &IB) {
+ assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ?
+ ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
+ "Lo is not <= Hi in range emission code!");
+
+ if (Inside) {
+ if (Lo == Hi) // Trivially false.
+ return new ICmpInst(ICmpInst::ICMP_NE, V, V);
+
+ // V >= Min && V < Hi --> V < Hi
+ if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
+ ICmpInst::Predicate pred = (isSigned ?
+ ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
+ return new ICmpInst(pred, V, Hi);
+ }
+
+ // Emit V-Lo <u Hi-Lo
+ Constant *NegLo = ConstantExpr::getNeg(Lo);
+ Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
+ Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
+ return new ICmpInst(ICmpInst::ICMP_ULT, Add, UpperBound);
+ }
+
+ if (Lo == Hi) // Trivially true.
+ return new ICmpInst(ICmpInst::ICMP_EQ, V, V);
+
+ // V < Min || V >= Hi -> V > Hi-1
+ Hi = SubOne(cast<ConstantInt>(Hi));
+ if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
+ ICmpInst::Predicate pred = (isSigned ?
+ ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
+ return new ICmpInst(pred, V, Hi);
+ }
+
+ // Emit V-Lo >u Hi-1-Lo
+ // Note that Hi has already had one subtracted from it, above.
+ ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo));
+ Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
+ Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
+ return new ICmpInst(ICmpInst::ICMP_UGT, Add, LowerBound);
+}
+
+// isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
+// any number of 0s on either side. The 1s are allowed to wrap from LSB to
+// MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
+// not, since all 1s are not contiguous.
+static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
+ const APInt& V = Val->getValue();
+ uint32_t BitWidth = Val->getType()->getBitWidth();
+ if (!APIntOps::isShiftedMask(BitWidth, V)) return false;
+
+ // look for the first zero bit after the run of ones
+ MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
+ // look for the first non-zero bit
+ ME = V.getActiveBits();
+ return true;
+}
+
+/// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
+/// where isSub determines whether the operator is a sub. If we can fold one of
+/// the following xforms:
+///
+/// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
+/// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
+/// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
+///
+/// return (A +/- B).
+///
+Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
+ ConstantInt *Mask, bool isSub,
+ Instruction &I) {
+ Instruction *LHSI = dyn_cast<Instruction>(LHS);
+ if (!LHSI || LHSI->getNumOperands() != 2 ||
+ !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
+
+ ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
+
+ switch (LHSI->getOpcode()) {
+ default: return 0;
+ case Instruction::And:
+ if (ConstantExpr::getAnd(N, Mask) == Mask) {
+ // If the AndRHS is a power of two minus one (0+1+), this is simple.
+ if ((Mask->getValue().countLeadingZeros() +
+ Mask->getValue().countPopulation()) ==
+ Mask->getValue().getBitWidth())
+ break;
+
+ // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
+ // part, we don't need any explicit masks to take them out of A. If that
+ // is all N is, ignore it.
+ uint32_t MB = 0, ME = 0;
+ if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
+ uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
+ APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
+ if (MaskedValueIsZero(RHS, Mask))
+ break;
+ }
+ }
+ return 0;
+ case Instruction::Or:
+ case Instruction::Xor:
+ // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
+ if ((Mask->getValue().countLeadingZeros() +
+ Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
+ && ConstantExpr::getAnd(N, Mask)->isNullValue())
+ break;
+ return 0;
+ }
+
+ if (isSub)
+ return Builder->CreateSub(LHSI->getOperand(0), RHS, "fold");
+ return Builder->CreateAdd(LHSI->getOperand(0), RHS, "fold");
+}
+
+/// FoldAndOfICmps - Fold (icmp)&(icmp) if possible.
+Instruction *InstCombiner::FoldAndOfICmps(Instruction &I,
+ ICmpInst *LHS, ICmpInst *RHS) {
+ Value *Val, *Val2;
+ ConstantInt *LHSCst, *RHSCst;
+ ICmpInst::Predicate LHSCC, RHSCC;
+
+ // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
+ if (!match(LHS, m_ICmp(LHSCC, m_Value(Val),
+ m_ConstantInt(LHSCst))) ||
+ !match(RHS, m_ICmp(RHSCC, m_Value(Val2),
+ m_ConstantInt(RHSCst))))
+ return 0;
+
+ if (LHSCst == RHSCst && LHSCC == RHSCC) {
+ // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C)
+ // where C is a power of 2
+ if (LHSCC == ICmpInst::ICMP_ULT &&
+ LHSCst->getValue().isPowerOf2()) {
+ Value *NewOr = Builder->CreateOr(Val, Val2);
+ return new ICmpInst(LHSCC, NewOr, LHSCst);
+ }
+
+ // (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0)
+ if (LHSCC == ICmpInst::ICMP_EQ && LHSCst->isZero()) {
+ Value *NewOr = Builder->CreateOr(Val, Val2);
+ return new ICmpInst(LHSCC, NewOr, LHSCst);
+ }
+ }
+
+ // From here on, we only handle:
+ // (icmp1 A, C1) & (icmp2 A, C2) --> something simpler.
+ if (Val != Val2) return 0;
+
+ // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
+ if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
+ RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
+ LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
+ RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
+ return 0;
+
+ // We can't fold (ugt x, C) & (sgt x, C2).
+ if (!PredicatesFoldable(LHSCC, RHSCC))
+ return 0;
+
+ // Ensure that the larger constant is on the RHS.
+ bool ShouldSwap;
+ if (CmpInst::isSigned(LHSCC) ||
+ (ICmpInst::isEquality(LHSCC) &&
+ CmpInst::isSigned(RHSCC)))
+ ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
+ else
+ ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
+
+ if (ShouldSwap) {
+ std::swap(LHS, RHS);
+ std::swap(LHSCst, RHSCst);
+ std::swap(LHSCC, RHSCC);
+ }
+
+ // At this point, we know we have have two icmp instructions
+ // comparing a value against two constants and and'ing the result
+ // together. Because of the above check, we know that we only have
+ // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
+ // (from the FoldICmpLogical check above), that the two constants
+ // are not equal and that the larger constant is on the RHS
+ assert(LHSCst != RHSCst && "Compares not folded above?");
+
+ switch (LHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ:
+ switch (RHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X == 13 & X == 15) -> false
+ case ICmpInst::ICMP_UGT: // (X == 13 & X > 15) -> false
+ case ICmpInst::ICMP_SGT: // (X == 13 & X > 15) -> false
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13
+ case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13
+ case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13
+ return ReplaceInstUsesWith(I, LHS);
+ }
+ case ICmpInst::ICMP_NE:
+ switch (RHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_ULT:
+ if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
+ return new ICmpInst(ICmpInst::ICMP_ULT, Val, LHSCst);
+ break; // (X != 13 & X u< 15) -> no change
+ case ICmpInst::ICMP_SLT:
+ if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
+ return new ICmpInst(ICmpInst::ICMP_SLT, Val, LHSCst);
+ break; // (X != 13 & X s< 15) -> no change
+ case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15
+ case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15
+ case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
+ return ReplaceInstUsesWith(I, RHS);
+ case ICmpInst::ICMP_NE:
+ if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
+ Constant *AddCST = ConstantExpr::getNeg(LHSCst);
+ Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
+ return new ICmpInst(ICmpInst::ICMP_UGT, Add,
+ ConstantInt::get(Add->getType(), 1));
+ }
+ break; // (X != 13 & X != 15) -> no change
+ }
+ break;
+ case ICmpInst::ICMP_ULT:
+ switch (RHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false
+ case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13
+ case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13
+ return ReplaceInstUsesWith(I, LHS);
+ case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change
+ break;
+ }
+ break;
+ case ICmpInst::ICMP_SLT:
+ switch (RHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X s< 13 & X == 15) -> false
+ case ICmpInst::ICMP_SGT: // (X s< 13 & X s> 15) -> false
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13
+ case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13
+ return ReplaceInstUsesWith(I, LHS);
+ case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change
+ break;
+ }
+ break;
+ case ICmpInst::ICMP_UGT:
+ switch (RHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X == 15
+ case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15
+ return ReplaceInstUsesWith(I, RHS);
+ case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE:
+ if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
+ return new ICmpInst(LHSCC, Val, RHSCst);
+ break; // (X u> 13 & X != 15) -> no change
+ case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) <u 1
+ return InsertRangeTest(Val, AddOne(LHSCst),
+ RHSCst, false, true, I);
+ case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change
+ break;
+ }
+ break;
+ case ICmpInst::ICMP_SGT:
+ switch (RHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X == 15
+ case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15
+ return ReplaceInstUsesWith(I, RHS);
+ case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE:
+ if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
+ return new ICmpInst(LHSCC, Val, RHSCst);
+ break; // (X s> 13 & X != 15) -> no change
+ case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1
+ return InsertRangeTest(Val, AddOne(LHSCst),
+ RHSCst, true, true, I);
+ case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change
+ break;
+ }
+ break;
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::FoldAndOfFCmps(Instruction &I, FCmpInst *LHS,
+ FCmpInst *RHS) {
+
+ if (LHS->getPredicate() == FCmpInst::FCMP_ORD &&
+ RHS->getPredicate() == FCmpInst::FCMP_ORD) {
+ // (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y)
+ if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
+ if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
+ // If either of the constants are nans, then the whole thing returns
+ // false.
+ if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ return new FCmpInst(FCmpInst::FCMP_ORD,
+ LHS->getOperand(0), RHS->getOperand(0));
+ }
+
+ // Handle vector zeros. This occurs because the canonical form of
+ // "fcmp ord x,x" is "fcmp ord x, 0".
+ if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
+ isa<ConstantAggregateZero>(RHS->getOperand(1)))
+ return new FCmpInst(FCmpInst::FCMP_ORD,
+ LHS->getOperand(0), RHS->getOperand(0));
+ return 0;
+ }
+
+ Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
+ Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
+ FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
+
+
+ if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
+ // Swap RHS operands to match LHS.
+ Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
+ std::swap(Op1LHS, Op1RHS);
+ }
+
+ if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
+ // Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y).
+ if (Op0CC == Op1CC)
+ return new FCmpInst((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
+
+ if (Op0CC == FCmpInst::FCMP_FALSE || Op1CC == FCmpInst::FCMP_FALSE)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ if (Op0CC == FCmpInst::FCMP_TRUE)
+ return ReplaceInstUsesWith(I, RHS);
+ if (Op1CC == FCmpInst::FCMP_TRUE)
+ return ReplaceInstUsesWith(I, LHS);
+
+ bool Op0Ordered;
+ bool Op1Ordered;
+ unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
+ unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
+ if (Op1Pred == 0) {
+ std::swap(LHS, RHS);
+ std::swap(Op0Pred, Op1Pred);
+ std::swap(Op0Ordered, Op1Ordered);
+ }
+ if (Op0Pred == 0) {
+ // uno && ueq -> uno && (uno || eq) -> ueq
+ // ord && olt -> ord && (ord && lt) -> olt
+ if (Op0Ordered == Op1Ordered)
+ return ReplaceInstUsesWith(I, RHS);
+
+ // uno && oeq -> uno && (ord && eq) -> false
+ // uno && ord -> false
+ if (!Op0Ordered)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ // ord && ueq -> ord && (uno || eq) -> oeq
+ return cast<Instruction>(getFCmpValue(true, Op1Pred,
+ Op0LHS, Op0RHS, Context));
+ }
+ }
+
+ return 0;
+}
+
+
+Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Value *V = SimplifyAndInst(Op0, Op1, TD))
+ return ReplaceInstUsesWith(I, V);
+
+ // See if we can simplify any instructions used by the instruction whose sole
+ // purpose is to compute bits we don't care about.
+ if (SimplifyDemandedInstructionBits(I))
+ return &I;
+
+ if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
+ const APInt &AndRHSMask = AndRHS->getValue();
+ APInt NotAndRHS(~AndRHSMask);
+
+ // Optimize a variety of ((val OP C1) & C2) combinations...
+ if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
+ Value *Op0LHS = Op0I->getOperand(0);
+ Value *Op0RHS = Op0I->getOperand(1);
+ switch (Op0I->getOpcode()) {
+ default: break;
+ case Instruction::Xor:
+ case Instruction::Or:
+ // If the mask is only needed on one incoming arm, push it up.
+ if (!Op0I->hasOneUse()) break;
+
+ if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
+ // Not masking anything out for the LHS, move to RHS.
+ Value *NewRHS = Builder->CreateAnd(Op0RHS, AndRHS,
+ Op0RHS->getName()+".masked");
+ return BinaryOperator::Create(Op0I->getOpcode(), Op0LHS, NewRHS);
+ }
+ if (!isa<Constant>(Op0RHS) &&
+ MaskedValueIsZero(Op0RHS, NotAndRHS)) {
+ // Not masking anything out for the RHS, move to LHS.
+ Value *NewLHS = Builder->CreateAnd(Op0LHS, AndRHS,
+ Op0LHS->getName()+".masked");
+ return BinaryOperator::Create(Op0I->getOpcode(), NewLHS, Op0RHS);
+ }
+
+ break;
+ case Instruction::Add:
+ // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
+ // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
+ // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
+ if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
+ return BinaryOperator::CreateAnd(V, AndRHS);
+ if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
+ return BinaryOperator::CreateAnd(V, AndRHS); // Add commutes
+ break;
+
+ case Instruction::Sub:
+ // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
+ // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
+ // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
+ if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
+ return BinaryOperator::CreateAnd(V, AndRHS);
+
+ // (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS
+ // has 1's for all bits that the subtraction with A might affect.
+ if (Op0I->hasOneUse()) {
+ uint32_t BitWidth = AndRHSMask.getBitWidth();
+ uint32_t Zeros = AndRHSMask.countLeadingZeros();
+ APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros);
+
+ ConstantInt *A = dyn_cast<ConstantInt>(Op0LHS);
+ if (!(A && A->isZero()) && // avoid infinite recursion.
+ MaskedValueIsZero(Op0LHS, Mask)) {
+ Value *NewNeg = Builder->CreateNeg(Op0RHS);
+ return BinaryOperator::CreateAnd(NewNeg, AndRHS);
+ }
+ }
+ break;
+
+ case Instruction::Shl:
+ case Instruction::LShr:
+ // (1 << x) & 1 --> zext(x == 0)
+ // (1 >> x) & 1 --> zext(x == 0)
+ if (AndRHSMask == 1 && Op0LHS == AndRHS) {
+ Value *NewICmp =
+ Builder->CreateICmpEQ(Op0RHS, Constant::getNullValue(I.getType()));
+ return new ZExtInst(NewICmp, I.getType());
+ }
+ break;
+ }
+
+ if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
+ if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
+ return Res;
+ } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
+ // If this is an integer truncation or change from signed-to-unsigned, and
+ // if the source is an and/or with immediate, transform it. This
+ // frequently occurs for bitfield accesses.
+ if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
+ if ((isa<TruncInst>(CI) || isa<BitCastInst>(CI)) &&
+ CastOp->getNumOperands() == 2)
+ if (ConstantInt *AndCI =dyn_cast<ConstantInt>(CastOp->getOperand(1))){
+ if (CastOp->getOpcode() == Instruction::And) {
+ // Change: and (cast (and X, C1) to T), C2
+ // into : and (cast X to T), trunc_or_bitcast(C1)&C2
+ // This will fold the two constants together, which may allow
+ // other simplifications.
+ Value *NewCast = Builder->CreateTruncOrBitCast(
+ CastOp->getOperand(0), I.getType(),
+ CastOp->getName()+".shrunk");
+ // trunc_or_bitcast(C1)&C2
+ Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
+ C3 = ConstantExpr::getAnd(C3, AndRHS);
+ return BinaryOperator::CreateAnd(NewCast, C3);
+ } else if (CastOp->getOpcode() == Instruction::Or) {
+ // Change: and (cast (or X, C1) to T), C2
+ // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
+ Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
+ if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS)
+ // trunc(C1)&C2
+ return ReplaceInstUsesWith(I, AndRHS);
+ }
+ }
+ }
+ }
+
+ // Try to fold constant and into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+
+ // (~A & ~B) == (~(A | B)) - De Morgan's Law
+ if (Value *Op0NotVal = dyn_castNotVal(Op0))
+ if (Value *Op1NotVal = dyn_castNotVal(Op1))
+ if (Op0->hasOneUse() && Op1->hasOneUse()) {
+ Value *Or = Builder->CreateOr(Op0NotVal, Op1NotVal,
+ I.getName()+".demorgan");
+ return BinaryOperator::CreateNot(Or);
+ }
+
+ {
+ Value *A = 0, *B = 0, *C = 0, *D = 0;
+ // (A|B) & ~(A&B) -> A^B
+ if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
+ match(Op1, m_Not(m_And(m_Value(C), m_Value(D)))) &&
+ ((A == C && B == D) || (A == D && B == C)))
+ return BinaryOperator::CreateXor(A, B);
+
+ // ~(A&B) & (A|B) -> A^B
+ if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
+ match(Op0, m_Not(m_And(m_Value(C), m_Value(D)))) &&
+ ((A == C && B == D) || (A == D && B == C)))
+ return BinaryOperator::CreateXor(A, B);
+
+ if (Op0->hasOneUse() &&
+ match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
+ if (A == Op1) { // (A^B)&A -> A&(A^B)
+ I.swapOperands(); // Simplify below
+ std::swap(Op0, Op1);
+ } else if (B == Op1) { // (A^B)&B -> B&(B^A)
+ cast<BinaryOperator>(Op0)->swapOperands();
+ I.swapOperands(); // Simplify below
+ std::swap(Op0, Op1);
+ }
+ }
+
+ if (Op1->hasOneUse() &&
+ match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
+ if (B == Op0) { // B&(A^B) -> B&(B^A)
+ cast<BinaryOperator>(Op1)->swapOperands();
+ std::swap(A, B);
+ }
+ if (A == Op0) // A&(A^B) -> A & ~B
+ return BinaryOperator::CreateAnd(A, Builder->CreateNot(B, "tmp"));
+ }
+
+ // (A&((~A)|B)) -> A&B
+ if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) ||
+ match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1)))))
+ return BinaryOperator::CreateAnd(A, Op1);
+ if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) ||
+ match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0)))))
+ return BinaryOperator::CreateAnd(A, Op0);
+ }
+
+ if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {
+ // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
+ if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
+ return R;
+
+ if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0))
+ if (Instruction *Res = FoldAndOfICmps(I, LHS, RHS))
+ return Res;
+ }
+
+ // fold (and (cast A), (cast B)) -> (cast (and A, B))
+ if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
+ if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
+ if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind ?
+ const Type *SrcTy = Op0C->getOperand(0)->getType();
+ if (SrcTy == Op1C->getOperand(0)->getType() &&
+ SrcTy->isIntOrIntVector() &&
+ // Only do this if the casts both really cause code to be generated.
+ ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
+ I.getType(), TD) &&
+ ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
+ I.getType(), TD)) {
+ Value *NewOp = Builder->CreateAnd(Op0C->getOperand(0),
+ Op1C->getOperand(0), I.getName());
+ return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
+ }
+ }
+
+ // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
+ if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
+ if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
+ if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
+ SI0->getOperand(1) == SI1->getOperand(1) &&
+ (SI0->hasOneUse() || SI1->hasOneUse())) {
+ Value *NewOp =
+ Builder->CreateAnd(SI0->getOperand(0), SI1->getOperand(0),
+ SI0->getName());
+ return BinaryOperator::Create(SI1->getOpcode(), NewOp,
+ SI1->getOperand(1));
+ }
+ }
+
+ // If and'ing two fcmp, try combine them into one.
+ if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
+ if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
+ if (Instruction *Res = FoldAndOfFCmps(I, LHS, RHS))
+ return Res;
+ }
+
+ return Changed ? &I : 0;
+}
+
+/// CollectBSwapParts - Analyze the specified subexpression and see if it is
+/// capable of providing pieces of a bswap. The subexpression provides pieces
+/// of a bswap if it is proven that each of the non-zero bytes in the output of
+/// the expression came from the corresponding "byte swapped" byte in some other
+/// value. For example, if the current subexpression is "(shl i32 %X, 24)" then
+/// we know that the expression deposits the low byte of %X into the high byte
+/// of the bswap result and that all other bytes are zero. This expression is
+/// accepted, the high byte of ByteValues is set to X to indicate a correct
+/// match.
+///
+/// This function returns true if the match was unsuccessful and false if so.
+/// On entry to the function the "OverallLeftShift" is a signed integer value
+/// indicating the number of bytes that the subexpression is later shifted. For
+/// example, if the expression is later right shifted by 16 bits, the
+/// OverallLeftShift value would be -2 on entry. This is used to specify which
+/// byte of ByteValues is actually being set.
+///
+/// Similarly, ByteMask is a bitmask where a bit is clear if its corresponding
+/// byte is masked to zero by a user. For example, in (X & 255), X will be
+/// processed with a bytemask of 1. Because bytemask is 32-bits, this limits
+/// this function to working on up to 32-byte (256 bit) values. ByteMask is
+/// always in the local (OverallLeftShift) coordinate space.
+///
+static bool CollectBSwapParts(Value *V, int OverallLeftShift, uint32_t ByteMask,
+ SmallVector<Value*, 8> &ByteValues) {
+ if (Instruction *I = dyn_cast<Instruction>(V)) {
+ // If this is an or instruction, it may be an inner node of the bswap.
+ if (I->getOpcode() == Instruction::Or) {
+ return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
+ ByteValues) ||
+ CollectBSwapParts(I->getOperand(1), OverallLeftShift, ByteMask,
+ ByteValues);
+ }
+
+ // If this is a logical shift by a constant multiple of 8, recurse with
+ // OverallLeftShift and ByteMask adjusted.
+ if (I->isLogicalShift() && isa<ConstantInt>(I->getOperand(1))) {
+ unsigned ShAmt =
+ cast<ConstantInt>(I->getOperand(1))->getLimitedValue(~0U);
+ // Ensure the shift amount is defined and of a byte value.
+ if ((ShAmt & 7) || (ShAmt > 8*ByteValues.size()))
+ return true;
+
+ unsigned ByteShift = ShAmt >> 3;
+ if (I->getOpcode() == Instruction::Shl) {
+ // X << 2 -> collect(X, +2)
+ OverallLeftShift += ByteShift;
+ ByteMask >>= ByteShift;
+ } else {
+ // X >>u 2 -> collect(X, -2)
+ OverallLeftShift -= ByteShift;
+ ByteMask <<= ByteShift;
+ ByteMask &= (~0U >> (32-ByteValues.size()));
+ }
+
+ if (OverallLeftShift >= (int)ByteValues.size()) return true;
+ if (OverallLeftShift <= -(int)ByteValues.size()) return true;
+
+ return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
+ ByteValues);
+ }
+
+ // If this is a logical 'and' with a mask that clears bytes, clear the
+ // corresponding bytes in ByteMask.
+ if (I->getOpcode() == Instruction::And &&
+ isa<ConstantInt>(I->getOperand(1))) {
+ // Scan every byte of the and mask, seeing if the byte is either 0 or 255.
+ unsigned NumBytes = ByteValues.size();
+ APInt Byte(I->getType()->getPrimitiveSizeInBits(), 255);
+ const APInt &AndMask = cast<ConstantInt>(I->getOperand(1))->getValue();
+
+ for (unsigned i = 0; i != NumBytes; ++i, Byte <<= 8) {
+ // If this byte is masked out by a later operation, we don't care what
+ // the and mask is.
+ if ((ByteMask & (1 << i)) == 0)
+ continue;
+
+ // If the AndMask is all zeros for this byte, clear the bit.
+ APInt MaskB = AndMask & Byte;
+ if (MaskB == 0) {
+ ByteMask &= ~(1U << i);
+ continue;
+ }
+
+ // If the AndMask is not all ones for this byte, it's not a bytezap.
+ if (MaskB != Byte)
+ return true;
+
+ // Otherwise, this byte is kept.
+ }
+
+ return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
+ ByteValues);
+ }
+ }
+
+ // Okay, we got to something that isn't a shift, 'or' or 'and'. This must be
+ // the input value to the bswap. Some observations: 1) if more than one byte
+ // is demanded from this input, then it could not be successfully assembled
+ // into a byteswap. At least one of the two bytes would not be aligned with
+ // their ultimate destination.
+ if (!isPowerOf2_32(ByteMask)) return true;
+ unsigned InputByteNo = CountTrailingZeros_32(ByteMask);
+
+ // 2) The input and ultimate destinations must line up: if byte 3 of an i32
+ // is demanded, it needs to go into byte 0 of the result. This means that the
+ // byte needs to be shifted until it lands in the right byte bucket. The
+ // shift amount depends on the position: if the byte is coming from the high
+ // part of the value (e.g. byte 3) then it must be shifted right. If from the
+ // low part, it must be shifted left.
+ unsigned DestByteNo = InputByteNo + OverallLeftShift;
+ if (InputByteNo < ByteValues.size()/2) {
+ if (ByteValues.size()-1-DestByteNo != InputByteNo)
+ return true;
+ } else {
+ if (ByteValues.size()-1-DestByteNo != InputByteNo)
+ return true;
+ }
+
+ // If the destination byte value is already defined, the values are or'd
+ // together, which isn't a bswap (unless it's an or of the same bits).
+ if (ByteValues[DestByteNo] && ByteValues[DestByteNo] != V)
+ return true;
+ ByteValues[DestByteNo] = V;
+ return false;
+}
+
+/// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom.
+/// If so, insert the new bswap intrinsic and return it.
+Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
+ const IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
+ if (!ITy || ITy->getBitWidth() % 16 ||
+ // ByteMask only allows up to 32-byte values.
+ ITy->getBitWidth() > 32*8)
+ return 0; // Can only bswap pairs of bytes. Can't do vectors.
+
+ /// ByteValues - For each byte of the result, we keep track of which value
+ /// defines each byte.
+ SmallVector<Value*, 8> ByteValues;
+ ByteValues.resize(ITy->getBitWidth()/8);
+
+ // Try to find all the pieces corresponding to the bswap.
+ uint32_t ByteMask = ~0U >> (32-ByteValues.size());
+ if (CollectBSwapParts(&I, 0, ByteMask, ByteValues))
+ return 0;
+
+ // Check to see if all of the bytes come from the same value.
+ Value *V = ByteValues[0];
+ if (V == 0) return 0; // Didn't find a byte? Must be zero.
+
+ // Check to make sure that all of the bytes come from the same value.
+ for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
+ if (ByteValues[i] != V)
+ return 0;
+ const Type *Tys[] = { ITy };
+ Module *M = I.getParent()->getParent()->getParent();
+ Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1);
+ return CallInst::Create(F, V);
+}
+
+/// MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D). Check
+/// If A is (cond?-1:0) and either B or D is ~(cond?-1,0) or (cond?0,-1), then
+/// we can simplify this expression to "cond ? C : D or B".
+static Instruction *MatchSelectFromAndOr(Value *A, Value *B,
+ Value *C, Value *D,
+ LLVMContext *Context) {
+ // If A is not a select of -1/0, this cannot match.
+ Value *Cond = 0;
+ if (!match(A, m_SelectCst<-1, 0>(m_Value(Cond))))
+ return 0;
+
+ // ((cond?-1:0)&C) | (B&(cond?0:-1)) -> cond ? C : B.
+ if (match(D, m_SelectCst<0, -1>(m_Specific(Cond))))
+ return SelectInst::Create(Cond, C, B);
+ if (match(D, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond)))))
+ return SelectInst::Create(Cond, C, B);
+ // ((cond?-1:0)&C) | ((cond?0:-1)&D) -> cond ? C : D.
+ if (match(B, m_SelectCst<0, -1>(m_Specific(Cond))))
+ return SelectInst::Create(Cond, C, D);
+ if (match(B, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond)))))
+ return SelectInst::Create(Cond, C, D);
+ return 0;
+}
+
+/// FoldOrOfICmps - Fold (icmp)|(icmp) if possible.
+Instruction *InstCombiner::FoldOrOfICmps(Instruction &I,
+ ICmpInst *LHS, ICmpInst *RHS) {
+ Value *Val, *Val2;
+ ConstantInt *LHSCst, *RHSCst;
+ ICmpInst::Predicate LHSCC, RHSCC;
+
+ // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2).
+ if (!match(LHS, m_ICmp(LHSCC, m_Value(Val), m_ConstantInt(LHSCst))) ||
+ !match(RHS, m_ICmp(RHSCC, m_Value(Val2), m_ConstantInt(RHSCst))))
+ return 0;
+
+
+ // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0)
+ if (LHSCst == RHSCst && LHSCC == RHSCC &&
+ LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) {
+ Value *NewOr = Builder->CreateOr(Val, Val2);
+ return new ICmpInst(LHSCC, NewOr, LHSCst);
+ }
+
+ // From here on, we only handle:
+ // (icmp1 A, C1) | (icmp2 A, C2) --> something simpler.
+ if (Val != Val2) return 0;
+
+ // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
+ if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
+ RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
+ LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
+ RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
+ return 0;
+
+ // We can't fold (ugt x, C) | (sgt x, C2).
+ if (!PredicatesFoldable(LHSCC, RHSCC))
+ return 0;
+
+ // Ensure that the larger constant is on the RHS.
+ bool ShouldSwap;
+ if (CmpInst::isSigned(LHSCC) ||
+ (ICmpInst::isEquality(LHSCC) &&
+ CmpInst::isSigned(RHSCC)))
+ ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
+ else
+ ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
+
+ if (ShouldSwap) {
+ std::swap(LHS, RHS);
+ std::swap(LHSCst, RHSCst);
+ std::swap(LHSCC, RHSCC);
+ }
+
+ // At this point, we know we have have two icmp instructions
+ // comparing a value against two constants and or'ing the result
+ // together. Because of the above check, we know that we only have
+ // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
+ // FoldICmpLogical check above), that the two constants are not
+ // equal.
+ assert(LHSCst != RHSCst && "Compares not folded above?");
+
+ switch (LHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ:
+ switch (RHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ:
+ if (LHSCst == SubOne(RHSCst)) {
+ // (X == 13 | X == 14) -> X-13 <u 2
+ Constant *AddCST = ConstantExpr::getNeg(LHSCst);
+ Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
+ AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
+ return new ICmpInst(ICmpInst::ICMP_ULT, Add, AddCST);
+ }
+ break; // (X == 13 | X == 15) -> no change
+ case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
+ case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15
+ case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15
+ case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15
+ return ReplaceInstUsesWith(I, RHS);
+ }
+ break;
+ case ICmpInst::ICMP_NE:
+ switch (RHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13
+ case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13
+ case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13
+ return ReplaceInstUsesWith(I, LHS);
+ case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true
+ case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true
+ case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ }
+ break;
+ case ICmpInst::ICMP_ULT:
+ switch (RHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
+ break;
+ case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2
+ // If RHSCst is [us]MAXINT, it is always false. Not handling
+ // this can cause overflow.
+ if (RHSCst->isMaxValue(false))
+ return ReplaceInstUsesWith(I, LHS);
+ return InsertRangeTest(Val, LHSCst, AddOne(RHSCst),
+ false, false, I);
+ case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15
+ case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15
+ return ReplaceInstUsesWith(I, RHS);
+ case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change
+ break;
+ }
+ break;
+ case ICmpInst::ICMP_SLT:
+ switch (RHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
+ break;
+ case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2
+ // If RHSCst is [us]MAXINT, it is always false. Not handling
+ // this can cause overflow.
+ if (RHSCst->isMaxValue(true))
+ return ReplaceInstUsesWith(I, LHS);
+ return InsertRangeTest(Val, LHSCst, AddOne(RHSCst),
+ true, false, I);
+ case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15
+ case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15
+ return ReplaceInstUsesWith(I, RHS);
+ case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change
+ break;
+ }
+ break;
+ case ICmpInst::ICMP_UGT:
+ switch (RHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13
+ case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13
+ return ReplaceInstUsesWith(I, LHS);
+ case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true
+ case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change
+ break;
+ }
+ break;
+ case ICmpInst::ICMP_SGT:
+ switch (RHSCC) {
+ default: llvm_unreachable("Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13
+ case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13
+ return ReplaceInstUsesWith(I, LHS);
+ case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true
+ case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change
+ break;
+ }
+ break;
+ }
+ return 0;
+}
+
+Instruction *InstCombiner::FoldOrOfFCmps(Instruction &I, FCmpInst *LHS,
+ FCmpInst *RHS) {
+ if (LHS->getPredicate() == FCmpInst::FCMP_UNO &&
+ RHS->getPredicate() == FCmpInst::FCMP_UNO &&
+ LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) {
+ if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
+ if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
+ // If either of the constants are nans, then the whole thing returns
+ // true.
+ if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+
+ // Otherwise, no need to compare the two constants, compare the
+ // rest.
+ return new FCmpInst(FCmpInst::FCMP_UNO,
+ LHS->getOperand(0), RHS->getOperand(0));
+ }
+
+ // Handle vector zeros. This occurs because the canonical form of
+ // "fcmp uno x,x" is "fcmp uno x, 0".
+ if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
+ isa<ConstantAggregateZero>(RHS->getOperand(1)))
+ return new FCmpInst(FCmpInst::FCMP_UNO,
+ LHS->getOperand(0), RHS->getOperand(0));
+
+ return 0;
+ }
+
+ Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
+ Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
+ FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
+
+ if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
+ // Swap RHS operands to match LHS.
+ Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
+ std::swap(Op1LHS, Op1RHS);
+ }
+ if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
+ // Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y).
+ if (Op0CC == Op1CC)
+ return new FCmpInst((FCmpInst::Predicate)Op0CC,
+ Op0LHS, Op0RHS);
+ if (Op0CC == FCmpInst::FCMP_TRUE || Op1CC == FCmpInst::FCMP_TRUE)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ if (Op0CC == FCmpInst::FCMP_FALSE)
+ return ReplaceInstUsesWith(I, RHS);
+ if (Op1CC == FCmpInst::FCMP_FALSE)
+ return ReplaceInstUsesWith(I, LHS);
+ bool Op0Ordered;
+ bool Op1Ordered;
+ unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
+ unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
+ if (Op0Ordered == Op1Ordered) {
+ // If both are ordered or unordered, return a new fcmp with
+ // or'ed predicates.
+ Value *RV = getFCmpValue(Op0Ordered, Op0Pred|Op1Pred,
+ Op0LHS, Op0RHS, Context);
+ if (Instruction *I = dyn_cast<Instruction>(RV))
+ return I;
+ // Otherwise, it's a constant boolean value...
+ return ReplaceInstUsesWith(I, RV);
+ }
+ }
+ return 0;
+}
+
+/// FoldOrWithConstants - This helper function folds:
+///
+/// ((A | B) & C1) | (B & C2)
+///
+/// into:
+///
+/// (A & C1) | B
+///
+/// when the XOR of the two constants is "all ones" (-1).
+Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op,
+ Value *A, Value *B, Value *C) {
+ ConstantInt *CI1 = dyn_cast<ConstantInt>(C);
+ if (!CI1) return 0;
+
+ Value *V1 = 0;
+ ConstantInt *CI2 = 0;
+ if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return 0;
+
+ APInt Xor = CI1->getValue() ^ CI2->getValue();
+ if (!Xor.isAllOnesValue()) return 0;
+
+ if (V1 == A || V1 == B) {
+ Value *NewOp = Builder->CreateAnd((V1 == A) ? B : A, CI1);
+ return BinaryOperator::CreateOr(NewOp, V1);
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitOr(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Value *V = SimplifyOrInst(Op0, Op1, TD))
+ return ReplaceInstUsesWith(I, V);
+
+
+ // See if we can simplify any instructions used by the instruction whose sole
+ // purpose is to compute bits we don't care about.
+ if (SimplifyDemandedInstructionBits(I))
+ return &I;
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+ ConstantInt *C1 = 0; Value *X = 0;
+ // (X & C1) | C2 --> (X | C2) & (C1|C2)
+ if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) &&
+ isOnlyUse(Op0)) {
+ Value *Or = Builder->CreateOr(X, RHS);
+ Or->takeName(Op0);
+ return BinaryOperator::CreateAnd(Or,
+ ConstantInt::get(*Context, RHS->getValue() | C1->getValue()));
+ }
+
+ // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
+ if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) &&
+ isOnlyUse(Op0)) {
+ Value *Or = Builder->CreateOr(X, RHS);
+ Or->takeName(Op0);
+ return BinaryOperator::CreateXor(Or,
+ ConstantInt::get(*Context, C1->getValue() & ~RHS->getValue()));
+ }
+
+ // Try to fold constant and into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+ Value *A = 0, *B = 0;
+ ConstantInt *C1 = 0, *C2 = 0;
+
+ // (A | B) | C and A | (B | C) -> bswap if possible.
+ // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
+ if (match(Op0, m_Or(m_Value(), m_Value())) ||
+ match(Op1, m_Or(m_Value(), m_Value())) ||
+ (match(Op0, m_Shift(m_Value(), m_Value())) &&
+ match(Op1, m_Shift(m_Value(), m_Value())))) {
+ if (Instruction *BSwap = MatchBSwap(I))
+ return BSwap;
+ }
+
+ // (X^C)|Y -> (X|Y)^C iff Y&C == 0
+ if (Op0->hasOneUse() &&
+ match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
+ MaskedValueIsZero(Op1, C1->getValue())) {
+ Value *NOr = Builder->CreateOr(A, Op1);
+ NOr->takeName(Op0);
+ return BinaryOperator::CreateXor(NOr, C1);
+ }
+
+ // Y|(X^C) -> (X|Y)^C iff Y&C == 0
+ if (Op1->hasOneUse() &&
+ match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
+ MaskedValueIsZero(Op0, C1->getValue())) {
+ Value *NOr = Builder->CreateOr(A, Op0);
+ NOr->takeName(Op0);
+ return BinaryOperator::CreateXor(NOr, C1);
+ }
+
+ // (A & C)|(B & D)
+ Value *C = 0, *D = 0;
+ if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
+ match(Op1, m_And(m_Value(B), m_Value(D)))) {
+ Value *V1 = 0, *V2 = 0, *V3 = 0;
+ C1 = dyn_cast<ConstantInt>(C);
+ C2 = dyn_cast<ConstantInt>(D);
+ if (C1 && C2) { // (A & C1)|(B & C2)
+ // If we have: ((V + N) & C1) | (V & C2)
+ // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
+ // replace with V+N.
+ if (C1->getValue() == ~C2->getValue()) {
+ if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+
+ match(A, m_Add(m_Value(V1), m_Value(V2)))) {
+ // Add commutes, try both ways.
+ if (V1 == B && MaskedValueIsZero(V2, C2->getValue()))
+ return ReplaceInstUsesWith(I, A);
+ if (V2 == B && MaskedValueIsZero(V1, C2->getValue()))
+ return ReplaceInstUsesWith(I, A);
+ }
+ // Or commutes, try both ways.
+ if ((C1->getValue() & (C1->getValue()+1)) == 0 &&
+ match(B, m_Add(m_Value(V1), m_Value(V2)))) {
+ // Add commutes, try both ways.
+ if (V1 == A && MaskedValueIsZero(V2, C1->getValue()))
+ return ReplaceInstUsesWith(I, B);
+ if (V2 == A && MaskedValueIsZero(V1, C1->getValue()))
+ return ReplaceInstUsesWith(I, B);
+ }
+ }
+
+ // ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2)
+ // iff (C1&C2) == 0 and (N&~C1) == 0
+ if ((C1->getValue() & C2->getValue()) == 0) {
+ if (match(A, m_Or(m_Value(V1), m_Value(V2))) &&
+ ((V1 == B && MaskedValueIsZero(V2, ~C1->getValue())) || // (V|N)
+ (V2 == B && MaskedValueIsZero(V1, ~C1->getValue())))) // (N|V)
+ return BinaryOperator::CreateAnd(A,
+ ConstantInt::get(A->getContext(),
+ C1->getValue()|C2->getValue()));
+ // Or commutes, try both ways.
+ if (match(B, m_Or(m_Value(V1), m_Value(V2))) &&
+ ((V1 == A && MaskedValueIsZero(V2, ~C2->getValue())) || // (V|N)
+ (V2 == A && MaskedValueIsZero(V1, ~C2->getValue())))) // (N|V)
+ return BinaryOperator::CreateAnd(B,
+ ConstantInt::get(B->getContext(),
+ C1->getValue()|C2->getValue()));
+ }
+ }
+
+ // Check to see if we have any common things being and'ed. If so, find the
+ // terms for V1 & (V2|V3).
+ if (isOnlyUse(Op0) || isOnlyUse(Op1)) {
+ V1 = 0;
+ if (A == B) // (A & C)|(A & D) == A & (C|D)
+ V1 = A, V2 = C, V3 = D;
+ else if (A == D) // (A & C)|(B & A) == A & (B|C)
+ V1 = A, V2 = B, V3 = C;
+ else if (C == B) // (A & C)|(C & D) == C & (A|D)
+ V1 = C, V2 = A, V3 = D;
+ else if (C == D) // (A & C)|(B & C) == C & (A|B)
+ V1 = C, V2 = A, V3 = B;
+
+ if (V1) {
+ Value *Or = Builder->CreateOr(V2, V3, "tmp");
+ return BinaryOperator::CreateAnd(V1, Or);
+ }
+ }
+
+ // (A & (C0?-1:0)) | (B & ~(C0?-1:0)) -> C0 ? A : B, and commuted variants
+ if (Instruction *Match = MatchSelectFromAndOr(A, B, C, D, Context))
+ return Match;
+ if (Instruction *Match = MatchSelectFromAndOr(B, A, D, C, Context))
+ return Match;
+ if (Instruction *Match = MatchSelectFromAndOr(C, B, A, D, Context))
+ return Match;
+ if (Instruction *Match = MatchSelectFromAndOr(D, A, B, C, Context))
+ return Match;
+
+ // ((A&~B)|(~A&B)) -> A^B
+ if ((match(C, m_Not(m_Specific(D))) &&
+ match(B, m_Not(m_Specific(A)))))
+ return BinaryOperator::CreateXor(A, D);
+ // ((~B&A)|(~A&B)) -> A^B
+ if ((match(A, m_Not(m_Specific(D))) &&
+ match(B, m_Not(m_Specific(C)))))
+ return BinaryOperator::CreateXor(C, D);
+ // ((A&~B)|(B&~A)) -> A^B
+ if ((match(C, m_Not(m_Specific(B))) &&
+ match(D, m_Not(m_Specific(A)))))
+ return BinaryOperator::CreateXor(A, B);
+ // ((~B&A)|(B&~A)) -> A^B
+ if ((match(A, m_Not(m_Specific(B))) &&
+ match(D, m_Not(m_Specific(C)))))
+ return BinaryOperator::CreateXor(C, B);
+ }
+
+ // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
+ if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
+ if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
+ if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
+ SI0->getOperand(1) == SI1->getOperand(1) &&
+ (SI0->hasOneUse() || SI1->hasOneUse())) {
+ Value *NewOp = Builder->CreateOr(SI0->getOperand(0), SI1->getOperand(0),
+ SI0->getName());
+ return BinaryOperator::Create(SI1->getOpcode(), NewOp,
+ SI1->getOperand(1));
+ }
+ }
+
+ // ((A|B)&1)|(B&-2) -> (A&1) | B
+ if (match(Op0, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
+ match(Op0, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
+ Instruction *Ret = FoldOrWithConstants(I, Op1, A, B, C);
+ if (Ret) return Ret;
+ }
+ // (B&-2)|((A|B)&1) -> (A&1) | B
+ if (match(Op1, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
+ match(Op1, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
+ Instruction *Ret = FoldOrWithConstants(I, Op0, A, B, C);
+ if (Ret) return Ret;
+ }
+
+ // (~A | ~B) == (~(A & B)) - De Morgan's Law
+ if (Value *Op0NotVal = dyn_castNotVal(Op0))
+ if (Value *Op1NotVal = dyn_castNotVal(Op1))
+ if (Op0->hasOneUse() && Op1->hasOneUse()) {
+ Value *And = Builder->CreateAnd(Op0NotVal, Op1NotVal,
+ I.getName()+".demorgan");
+ return BinaryOperator::CreateNot(And);
+ }
+
+ // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
+ if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) {
+ if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
+ return R;
+
+ if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
+ if (Instruction *Res = FoldOrOfICmps(I, LHS, RHS))
+ return Res;
+ }
+
+ // fold (or (cast A), (cast B)) -> (cast (or A, B))
+ if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
+ if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
+ if (Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
+ if (!isa<ICmpInst>(Op0C->getOperand(0)) ||
+ !isa<ICmpInst>(Op1C->getOperand(0))) {
+ const Type *SrcTy = Op0C->getOperand(0)->getType();
+ if (SrcTy == Op1C->getOperand(0)->getType() &&
+ SrcTy->isIntOrIntVector() &&
+ // Only do this if the casts both really cause code to be
+ // generated.
+ ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
+ I.getType(), TD) &&
+ ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
+ I.getType(), TD)) {
+ Value *NewOp = Builder->CreateOr(Op0C->getOperand(0),
+ Op1C->getOperand(0), I.getName());
+ return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
+ }
+ }
+ }
+ }
+
+
+ // (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y)
+ if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
+ if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
+ if (Instruction *Res = FoldOrOfFCmps(I, LHS, RHS))
+ return Res;
+ }
+
+ return Changed ? &I : 0;
+}
+
+namespace {
+
+// XorSelf - Implements: X ^ X --> 0
+struct XorSelf {
+ Value *RHS;
+ XorSelf(Value *rhs) : RHS(rhs) {}
+ bool shouldApply(Value *LHS) const { return LHS == RHS; }
+ Instruction *apply(BinaryOperator &Xor) const {
+ return &Xor;
+ }
+};
+
+}
+
+Instruction *InstCombiner::visitXor(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (isa<UndefValue>(Op1)) {
+ if (isa<UndefValue>(Op0))
+ // Handle undef ^ undef -> 0 special case. This is a common
+ // idiom (misuse).
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
+ }
+
+ // xor X, X = 0, even if X is nested in a sequence of Xor's.
+ if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
+ assert(Result == &I && "AssociativeOpt didn't work?"); Result=Result;
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ }
+
+ // See if we can simplify any instructions used by the instruction whose sole
+ // purpose is to compute bits we don't care about.
+ if (SimplifyDemandedInstructionBits(I))
+ return &I;
+ if (isa<VectorType>(I.getType()))
+ if (isa<ConstantAggregateZero>(Op1))
+ return ReplaceInstUsesWith(I, Op0); // X ^ <0,0> -> X
+
+ // Is this a ~ operation?
+ if (Value *NotOp = dyn_castNotVal(&I)) {
+ if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) {
+ if (Op0I->getOpcode() == Instruction::And ||
+ Op0I->getOpcode() == Instruction::Or) {
+ // ~(~X & Y) --> (X | ~Y) - De Morgan's Law
+ // ~(~X | Y) === (X & ~Y) - De Morgan's Law
+ if (dyn_castNotVal(Op0I->getOperand(1)))
+ Op0I->swapOperands();
+ if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
+ Value *NotY =
+ Builder->CreateNot(Op0I->getOperand(1),
+ Op0I->getOperand(1)->getName()+".not");
+ if (Op0I->getOpcode() == Instruction::And)
+ return BinaryOperator::CreateOr(Op0NotVal, NotY);
+ return BinaryOperator::CreateAnd(Op0NotVal, NotY);
+ }
+
+ // ~(X & Y) --> (~X | ~Y) - De Morgan's Law
+ // ~(X | Y) === (~X & ~Y) - De Morgan's Law
+ if (isFreeToInvert(Op0I->getOperand(0)) &&
+ isFreeToInvert(Op0I->getOperand(1))) {
+ Value *NotX =
+ Builder->CreateNot(Op0I->getOperand(0), "notlhs");
+ Value *NotY =
+ Builder->CreateNot(Op0I->getOperand(1), "notrhs");
+ if (Op0I->getOpcode() == Instruction::And)
+ return BinaryOperator::CreateOr(NotX, NotY);
+ return BinaryOperator::CreateAnd(NotX, NotY);
+ }
+ }
+ }
+ }
+
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+ if (RHS->isOne() && Op0->hasOneUse()) {
+ // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
+ return new ICmpInst(ICI->getInversePredicate(),
+ ICI->getOperand(0), ICI->getOperand(1));
+
+ if (FCmpInst *FCI = dyn_cast<FCmpInst>(Op0))
+ return new FCmpInst(FCI->getInversePredicate(),
+ FCI->getOperand(0), FCI->getOperand(1));
+ }
+
+ // fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp).
+ if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
+ if (CmpInst *CI = dyn_cast<CmpInst>(Op0C->getOperand(0))) {
+ if (CI->hasOneUse() && Op0C->hasOneUse()) {
+ Instruction::CastOps Opcode = Op0C->getOpcode();
+ if ((Opcode == Instruction::ZExt || Opcode == Instruction::SExt) &&
+ (RHS == ConstantExpr::getCast(Opcode,
+ ConstantInt::getTrue(*Context),
+ Op0C->getDestTy()))) {
+ CI->setPredicate(CI->getInversePredicate());
+ return CastInst::Create(Opcode, CI, Op0C->getType());
+ }
+ }
+ }
+ }
+
+ if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
+ // ~(c-X) == X-c-1 == X+(-c-1)
+ if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
+ if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
+ Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
+ Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
+ ConstantInt::get(I.getType(), 1));
+ return BinaryOperator::CreateAdd(Op0I->getOperand(1), ConstantRHS);
+ }
+
+ if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
+ if (Op0I->getOpcode() == Instruction::Add) {
+ // ~(X-c) --> (-c-1)-X
+ if (RHS->isAllOnesValue()) {
+ Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
+ return BinaryOperator::CreateSub(
+ ConstantExpr::getSub(NegOp0CI,
+ ConstantInt::get(I.getType(), 1)),
+ Op0I->getOperand(0));
+ } else if (RHS->getValue().isSignBit()) {
+ // (X + C) ^ signbit -> (X + C + signbit)
+ Constant *C = ConstantInt::get(*Context,
+ RHS->getValue() + Op0CI->getValue());
+ return BinaryOperator::CreateAdd(Op0I->getOperand(0), C);
+
+ }
+ } else if (Op0I->getOpcode() == Instruction::Or) {
+ // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
+ if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) {
+ Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
+ // Anything in both C1 and C2 is known to be zero, remove it from
+ // NewRHS.
+ Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHS);
+ NewRHS = ConstantExpr::getAnd(NewRHS,
+ ConstantExpr::getNot(CommonBits));
+ Worklist.Add(Op0I);
+ I.setOperand(0, Op0I->getOperand(0));
+ I.setOperand(1, NewRHS);
+ return &I;
+ }
+ }
+ }
+ }
+
+ // Try to fold constant and into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+ if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
+ if (X == Op1)
+ return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+ if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
+ if (X == Op0)
+ return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+
+ BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
+ if (Op1I) {
+ Value *A, *B;
+ if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
+ if (A == Op0) { // B^(B|A) == (A|B)^B
+ Op1I->swapOperands();
+ I.swapOperands();
+ std::swap(Op0, Op1);
+ } else if (B == Op0) { // B^(A|B) == (A|B)^B
+ I.swapOperands(); // Simplified below.
+ std::swap(Op0, Op1);
+ }
+ } else if (match(Op1I, m_Xor(m_Specific(Op0), m_Value(B)))) {
+ return ReplaceInstUsesWith(I, B); // A^(A^B) == B
+ } else if (match(Op1I, m_Xor(m_Value(A), m_Specific(Op0)))) {
+ return ReplaceInstUsesWith(I, A); // A^(B^A) == B
+ } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) &&
+ Op1I->hasOneUse()){
+ if (A == Op0) { // A^(A&B) -> A^(B&A)
+ Op1I->swapOperands();
+ std::swap(A, B);
+ }
+ if (B == Op0) { // A^(B&A) -> (B&A)^A
+ I.swapOperands(); // Simplified below.
+ std::swap(Op0, Op1);
+ }
+ }
+ }
+
+ BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
+ if (Op0I) {
+ Value *A, *B;
+ if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
+ Op0I->hasOneUse()) {
+ if (A == Op1) // (B|A)^B == (A|B)^B
+ std::swap(A, B);
+ if (B == Op1) // (A|B)^B == A & ~B
+ return BinaryOperator::CreateAnd(A, Builder->CreateNot(Op1, "tmp"));
+ } else if (match(Op0I, m_Xor(m_Specific(Op1), m_Value(B)))) {
+ return ReplaceInstUsesWith(I, B); // (A^B)^A == B
+ } else if (match(Op0I, m_Xor(m_Value(A), m_Specific(Op1)))) {
+ return ReplaceInstUsesWith(I, A); // (B^A)^A == B
+ } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
+ Op0I->hasOneUse()){
+ if (A == Op1) // (A&B)^A -> (B&A)^A
+ std::swap(A, B);
+ if (B == Op1 && // (B&A)^A == ~B & A
+ !isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C
+ return BinaryOperator::CreateAnd(Builder->CreateNot(A, "tmp"), Op1);
+ }
+ }
+ }
+
+ // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
+ if (Op0I && Op1I && Op0I->isShift() &&
+ Op0I->getOpcode() == Op1I->getOpcode() &&
+ Op0I->getOperand(1) == Op1I->getOperand(1) &&
+ (Op1I->hasOneUse() || Op1I->hasOneUse())) {
+ Value *NewOp =
+ Builder->CreateXor(Op0I->getOperand(0), Op1I->getOperand(0),
+ Op0I->getName());
+ return BinaryOperator::Create(Op1I->getOpcode(), NewOp,
+ Op1I->getOperand(1));
+ }
+
+ if (Op0I && Op1I) {
+ Value *A, *B, *C, *D;
+ // (A & B)^(A | B) -> A ^ B
+ if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
+ match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
+ if ((A == C && B == D) || (A == D && B == C))
+ return BinaryOperator::CreateXor(A, B);
+ }
+ // (A | B)^(A & B) -> A ^ B
+ if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
+ match(Op1I, m_And(m_Value(C), m_Value(D)))) {
+ if ((A == C && B == D) || (A == D && B == C))
+ return BinaryOperator::CreateXor(A, B);
+ }
+
+ // (A & B)^(C & D)
+ if ((Op0I->hasOneUse() || Op1I->hasOneUse()) &&
+ match(Op0I, m_And(m_Value(A), m_Value(B))) &&
+ match(Op1I, m_And(m_Value(C), m_Value(D)))) {
+ // (X & Y)^(X & Y) -> (Y^Z) & X
+ Value *X = 0, *Y = 0, *Z = 0;
+ if (A == C)
+ X = A, Y = B, Z = D;
+ else if (A == D)
+ X = A, Y = B, Z = C;
+ else if (B == C)
+ X = B, Y = A, Z = D;
+ else if (B == D)
+ X = B, Y = A, Z = C;
+
+ if (X) {
+ Value *NewOp = Builder->CreateXor(Y, Z, Op0->getName());
+ return BinaryOperator::CreateAnd(NewOp, X);
+ }
+ }
+ }
+
+ // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
+ if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
+ if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
+ return R;
+
+ // fold (xor (cast A), (cast B)) -> (cast (xor A, B))
+ if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
+ if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
+ if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
+ const Type *SrcTy = Op0C->getOperand(0)->getType();
+ if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
+ // Only do this if the casts both really cause code to be generated.
+ ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
+ I.getType(), TD) &&
+ ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
+ I.getType(), TD)) {
+ Value *NewOp = Builder->CreateXor(Op0C->getOperand(0),
+ Op1C->getOperand(0), I.getName());
+ return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
+ }
+ }
+ }
+
+ return Changed ? &I : 0;
+}
+
+static ConstantInt *ExtractElement(Constant *V, Constant *Idx,
+ LLVMContext *Context) {
+ return cast<ConstantInt>(ConstantExpr::getExtractElement(V, Idx));
+}
+
+static bool HasAddOverflow(ConstantInt *Result,
+ ConstantInt *In1, ConstantInt *In2,
+ bool IsSigned) {
+ if (IsSigned)
+ if (In2->getValue().isNegative())
+ return Result->getValue().sgt(In1->getValue());
+ else
+ return Result->getValue().slt(In1->getValue());
+ else
+ return Result->getValue().ult(In1->getValue());
+}
+
+/// AddWithOverflow - Compute Result = In1+In2, returning true if the result
+/// overflowed for this type.
+static bool AddWithOverflow(Constant *&Result, Constant *In1,
+ Constant *In2, LLVMContext *Context,
+ bool IsSigned = false) {
+ Result = ConstantExpr::getAdd(In1, In2);
+
+ if (const VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
+ for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
+ Constant *Idx = ConstantInt::get(Type::getInt32Ty(*Context), i);
+ if (HasAddOverflow(ExtractElement(Result, Idx, Context),
+ ExtractElement(In1, Idx, Context),
+ ExtractElement(In2, Idx, Context),
+ IsSigned))
+ return true;
+ }
+ return false;
+ }
+
+ return HasAddOverflow(cast<ConstantInt>(Result),
+ cast<ConstantInt>(In1), cast<ConstantInt>(In2),
+ IsSigned);
+}
+
+static bool HasSubOverflow(ConstantInt *Result,
+ ConstantInt *In1, ConstantInt *In2,
+ bool IsSigned) {
+ if (IsSigned)
+ if (In2->getValue().isNegative())
+ return Result->getValue().slt(In1->getValue());
+ else
+ return Result->getValue().sgt(In1->getValue());
+ else
+ return Result->getValue().ugt(In1->getValue());
+}
+
+/// SubWithOverflow - Compute Result = In1-In2, returning true if the result
+/// overflowed for this type.
+static bool SubWithOverflow(Constant *&Result, Constant *In1,
+ Constant *In2, LLVMContext *Context,
+ bool IsSigned = false) {
+ Result = ConstantExpr::getSub(In1, In2);
+
+ if (const VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
+ for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
+ Constant *Idx = ConstantInt::get(Type::getInt32Ty(*Context), i);
+ if (HasSubOverflow(ExtractElement(Result, Idx, Context),
+ ExtractElement(In1, Idx, Context),
+ ExtractElement(In2, Idx, Context),
+ IsSigned))
+ return true;
+ }
+ return false;
+ }
+
+ return HasSubOverflow(cast<ConstantInt>(Result),
+ cast<ConstantInt>(In1), cast<ConstantInt>(In2),
+ IsSigned);
+}
+
+
+/// FoldGEPICmp - Fold comparisons between a GEP instruction and something
+/// else. At this point we know that the GEP is on the LHS of the comparison.
+Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
+ ICmpInst::Predicate Cond,
+ Instruction &I) {
+ // Look through bitcasts.
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(RHS))
+ RHS = BCI->getOperand(0);
+
+ Value *PtrBase = GEPLHS->getOperand(0);
+ if (TD && PtrBase == RHS && GEPLHS->isInBounds()) {
+ // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
+ // This transformation (ignoring the base and scales) is valid because we
+ // know pointers can't overflow since the gep is inbounds. See if we can
+ // output an optimized form.
+ Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, I, *this);
+
+ // If not, synthesize the offset the hard way.
+ if (Offset == 0)
+ Offset = EmitGEPOffset(GEPLHS, *this);
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
+ Constant::getNullValue(Offset->getType()));
+ } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
+ // If the base pointers are different, but the indices are the same, just
+ // compare the base pointer.
+ if (PtrBase != GEPRHS->getOperand(0)) {
+ bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
+ IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
+ GEPRHS->getOperand(0)->getType();
+ if (IndicesTheSame)
+ for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
+ if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
+ IndicesTheSame = false;
+ break;
+ }
+
+ // If all indices are the same, just compare the base pointers.
+ if (IndicesTheSame)
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond),
+ GEPLHS->getOperand(0), GEPRHS->getOperand(0));
+
+ // Otherwise, the base pointers are different and the indices are
+ // different, bail out.
+ return 0;
+ }
+
+ // If one of the GEPs has all zero indices, recurse.
+ bool AllZeros = true;
+ for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
+ if (!isa<Constant>(GEPLHS->getOperand(i)) ||
+ !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
+ AllZeros = false;
+ break;
+ }
+ if (AllZeros)
+ return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
+ ICmpInst::getSwappedPredicate(Cond), I);
+
+ // If the other GEP has all zero indices, recurse.
+ AllZeros = true;
+ for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
+ if (!isa<Constant>(GEPRHS->getOperand(i)) ||
+ !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
+ AllZeros = false;
+ break;
+ }
+ if (AllZeros)
+ return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
+
+ if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
+ // If the GEPs only differ by one index, compare it.
+ unsigned NumDifferences = 0; // Keep track of # differences.
+ unsigned DiffOperand = 0; // The operand that differs.
+ for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
+ if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
+ if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
+ GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
+ // Irreconcilable differences.
+ NumDifferences = 2;
+ break;
+ } else {
+ if (NumDifferences++) break;
+ DiffOperand = i;
+ }
+ }
+
+ if (NumDifferences == 0) // SAME GEP?
+ return ReplaceInstUsesWith(I, // No comparison is needed here.
+ ConstantInt::get(Type::getInt1Ty(*Context),
+ ICmpInst::isTrueWhenEqual(Cond)));
+
+ else if (NumDifferences == 1) {
+ Value *LHSV = GEPLHS->getOperand(DiffOperand);
+ Value *RHSV = GEPRHS->getOperand(DiffOperand);
+ // Make sure we do a signed comparison here.
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
+ }
+ }
+
+ // Only lower this if the icmp is the only user of the GEP or if we expect
+ // the result to fold to a constant!
+ if (TD &&
+ (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
+ (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
+ // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
+ Value *L = EmitGEPOffset(GEPLHS, *this);
+ Value *R = EmitGEPOffset(GEPRHS, *this);
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
+ }
+ }
+ return 0;
+}
+
+/// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible.
+///
+Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I,
+ Instruction *LHSI,
+ Constant *RHSC) {
+ if (!isa<ConstantFP>(RHSC)) return 0;
+ const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
+
+ // Get the width of the mantissa. We don't want to hack on conversions that
+ // might lose information from the integer, e.g. "i64 -> float"
+ int MantissaWidth = LHSI->getType()->getFPMantissaWidth();
+ if (MantissaWidth == -1) return 0; // Unknown.
+
+ // Check to see that the input is converted from an integer type that is small
+ // enough that preserves all bits. TODO: check here for "known" sign bits.
+ // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
+ unsigned InputSize = LHSI->getOperand(0)->getType()->getScalarSizeInBits();
+
+ // If this is a uitofp instruction, we need an extra bit to hold the sign.
+ bool LHSUnsigned = isa<UIToFPInst>(LHSI);
+ if (LHSUnsigned)
+ ++InputSize;
+
+ // If the conversion would lose info, don't hack on this.
+ if ((int)InputSize > MantissaWidth)
+ return 0;
+
+ // Otherwise, we can potentially simplify the comparison. We know that it
+ // will always come through as an integer value and we know the constant is
+ // not a NAN (it would have been previously simplified).
+ assert(!RHS.isNaN() && "NaN comparison not already folded!");
+
+ ICmpInst::Predicate Pred;
+ switch (I.getPredicate()) {
+ default: llvm_unreachable("Unexpected predicate!");
+ case FCmpInst::FCMP_UEQ:
+ case FCmpInst::FCMP_OEQ:
+ Pred = ICmpInst::ICMP_EQ;
+ break;
+ case FCmpInst::FCMP_UGT:
+ case FCmpInst::FCMP_OGT:
+ Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT;
+ break;
+ case FCmpInst::FCMP_UGE:
+ case FCmpInst::FCMP_OGE:
+ Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
+ break;
+ case FCmpInst::FCMP_ULT:
+ case FCmpInst::FCMP_OLT:
+ Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT;
+ break;
+ case FCmpInst::FCMP_ULE:
+ case FCmpInst::FCMP_OLE:
+ Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE;
+ break;
+ case FCmpInst::FCMP_UNE:
+ case FCmpInst::FCMP_ONE:
+ Pred = ICmpInst::ICMP_NE;
+ break;
+ case FCmpInst::FCMP_ORD:
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ case FCmpInst::FCMP_UNO:
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ }
+
+ const IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType());
+
+ // Now we know that the APFloat is a normal number, zero or inf.
+
+ // See if the FP constant is too large for the integer. For example,
+ // comparing an i8 to 300.0.
+ unsigned IntWidth = IntTy->getScalarSizeInBits();
+
+ if (!LHSUnsigned) {
+ // If the RHS value is > SignedMax, fold the comparison. This handles +INF
+ // and large values.
+ APFloat SMax(RHS.getSemantics(), APFloat::fcZero, false);
+ SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true,
+ APFloat::rmNearestTiesToEven);
+ if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0
+ if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT ||
+ Pred == ICmpInst::ICMP_SLE)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ }
+ } else {
+ // If the RHS value is > UnsignedMax, fold the comparison. This handles
+ // +INF and large values.
+ APFloat UMax(RHS.getSemantics(), APFloat::fcZero, false);
+ UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false,
+ APFloat::rmNearestTiesToEven);
+ if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0
+ if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT ||
+ Pred == ICmpInst::ICMP_ULE)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ }
+ }
+
+ if (!LHSUnsigned) {
+ // See if the RHS value is < SignedMin.
+ APFloat SMin(RHS.getSemantics(), APFloat::fcZero, false);
+ SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true,
+ APFloat::rmNearestTiesToEven);
+ if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0
+ if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT ||
+ Pred == ICmpInst::ICMP_SGE)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ }
+ }
+
+ // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
+ // [0, UMAX], but it may still be fractional. See if it is fractional by
+ // casting the FP value to the integer value and back, checking for equality.
+ // Don't do this for zero, because -0.0 is not fractional.
+ Constant *RHSInt = LHSUnsigned
+ ? ConstantExpr::getFPToUI(RHSC, IntTy)
+ : ConstantExpr::getFPToSI(RHSC, IntTy);
+ if (!RHS.isZero()) {
+ bool Equal = LHSUnsigned
+ ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC
+ : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC;
+ if (!Equal) {
+ // If we had a comparison against a fractional value, we have to adjust
+ // the compare predicate and sometimes the value. RHSC is rounded towards
+ // zero at this point.
+ switch (Pred) {
+ default: llvm_unreachable("Unexpected integer comparison!");
+ case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ case ICmpInst::ICMP_ULE:
+ // (float)int <= 4.4 --> int <= 4
+ // (float)int <= -4.4 --> false
+ if (RHS.isNegative())
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ break;
+ case ICmpInst::ICMP_SLE:
+ // (float)int <= 4.4 --> int <= 4
+ // (float)int <= -4.4 --> int < -4
+ if (RHS.isNegative())
+ Pred = ICmpInst::ICMP_SLT;
+ break;
+ case ICmpInst::ICMP_ULT:
+ // (float)int < -4.4 --> false
+ // (float)int < 4.4 --> int <= 4
+ if (RHS.isNegative())
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ Pred = ICmpInst::ICMP_ULE;
+ break;
+ case ICmpInst::ICMP_SLT:
+ // (float)int < -4.4 --> int < -4
+ // (float)int < 4.4 --> int <= 4
+ if (!RHS.isNegative())
+ Pred = ICmpInst::ICMP_SLE;
+ break;
+ case ICmpInst::ICMP_UGT:
+ // (float)int > 4.4 --> int > 4
+ // (float)int > -4.4 --> true
+ if (RHS.isNegative())
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ break;
+ case ICmpInst::ICMP_SGT:
+ // (float)int > 4.4 --> int > 4
+ // (float)int > -4.4 --> int >= -4
+ if (RHS.isNegative())
+ Pred = ICmpInst::ICMP_SGE;
+ break;
+ case ICmpInst::ICMP_UGE:
+ // (float)int >= -4.4 --> true
+ // (float)int >= 4.4 --> int > 4
+ if (!RHS.isNegative())
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ Pred = ICmpInst::ICMP_UGT;
+ break;
+ case ICmpInst::ICMP_SGE:
+ // (float)int >= -4.4 --> int >= -4
+ // (float)int >= 4.4 --> int > 4
+ if (!RHS.isNegative())
+ Pred = ICmpInst::ICMP_SGT;
+ break;
+ }
+ }
+ }
+
+ // Lower this FP comparison into an appropriate integer version of the
+ // comparison.
+ return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt);
+}
+
+/// FoldCmpLoadFromIndexedGlobal - Called we see this pattern:
+/// cmp pred (load (gep GV, ...)), cmpcst
+/// where GV is a global variable with a constant initializer. Try to simplify
+/// this into some simple computation that does not need the load. For example
+/// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3".
+///
+/// If AndCst is non-null, then the loaded value is masked with that constant
+/// before doing the comparison. This handles cases like "A[i]&4 == 0".
+Instruction *InstCombiner::
+FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV,
+ CmpInst &ICI, ConstantInt *AndCst) {
+ ConstantArray *Init = dyn_cast<ConstantArray>(GV->getInitializer());
+ if (Init == 0 || Init->getNumOperands() > 1024) return 0;
+
+ // There are many forms of this optimization we can handle, for now, just do
+ // the simple index into a single-dimensional array.
+ //
+ // Require: GEP GV, 0, i {{, constant indices}}
+ if (GEP->getNumOperands() < 3 ||
+ !isa<ConstantInt>(GEP->getOperand(1)) ||
+ !cast<ConstantInt>(GEP->getOperand(1))->isZero() ||
+ isa<Constant>(GEP->getOperand(2)))
+ return 0;
+
+ // Check that indices after the variable are constants and in-range for the
+ // type they index. Collect the indices. This is typically for arrays of
+ // structs.
+ SmallVector<unsigned, 4> LaterIndices;
+
+ const Type *EltTy = cast<ArrayType>(Init->getType())->getElementType();
+ for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) {
+ ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i));
+ if (Idx == 0) return 0; // Variable index.
+
+ uint64_t IdxVal = Idx->getZExtValue();
+ if ((unsigned)IdxVal != IdxVal) return 0; // Too large array index.
+
+ if (const StructType *STy = dyn_cast<StructType>(EltTy))
+ EltTy = STy->getElementType(IdxVal);
+ else if (const ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) {
+ if (IdxVal >= ATy->getNumElements()) return 0;
+ EltTy = ATy->getElementType();
+ } else {
+ return 0; // Unknown type.
+ }
+
+ LaterIndices.push_back(IdxVal);
+ }
+
+ enum { Overdefined = -3, Undefined = -2 };
+
+ // Variables for our state machines.
+
+ // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form
+ // "i == 47 | i == 87", where 47 is the first index the condition is true for,
+ // and 87 is the second (and last) index. FirstTrueElement is -2 when
+ // undefined, otherwise set to the first true element. SecondTrueElement is
+ // -2 when undefined, -3 when overdefined and >= 0 when that index is true.
+ int FirstTrueElement = Undefined, SecondTrueElement = Undefined;
+
+ // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the
+ // form "i != 47 & i != 87". Same state transitions as for true elements.
+ int FirstFalseElement = Undefined, SecondFalseElement = Undefined;
+
+ /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these
+ /// define a state machine that triggers for ranges of values that the index
+ /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'.
+ /// This is -2 when undefined, -3 when overdefined, and otherwise the last
+ /// index in the range (inclusive). We use -2 for undefined here because we
+ /// use relative comparisons and don't want 0-1 to match -1.
+ int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined;
+
+ // MagicBitvector - This is a magic bitvector where we set a bit if the
+ // comparison is true for element 'i'. If there are 64 elements or less in
+ // the array, this will fully represent all the comparison results.
+ uint64_t MagicBitvector = 0;
+
+
+ // Scan the array and see if one of our patterns matches.
+ Constant *CompareRHS = cast<Constant>(ICI.getOperand(1));
+ for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
+ Constant *Elt = Init->getOperand(i);
+
+ // If this is indexing an array of structures, get the structure element.
+ if (!LaterIndices.empty())
+ Elt = ConstantExpr::getExtractValue(Elt, LaterIndices.data(),
+ LaterIndices.size());
+
+ // If the element is masked, handle it.
+ if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst);
+
+ // Find out if the comparison would be true or false for the i'th element.
+ Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt,
+ CompareRHS, TD);
+ // If the result is undef for this element, ignore it.
+ if (isa<UndefValue>(C)) {
+ // Extend range state machines to cover this element in case there is an
+ // undef in the middle of the range.
+ if (TrueRangeEnd == (int)i-1)
+ TrueRangeEnd = i;
+ if (FalseRangeEnd == (int)i-1)
+ FalseRangeEnd = i;
+ continue;
+ }
+
+ // If we can't compute the result for any of the elements, we have to give
+ // up evaluating the entire conditional.
+ if (!isa<ConstantInt>(C)) return 0;
+
+ // Otherwise, we know if the comparison is true or false for this element,
+ // update our state machines.
+ bool IsTrueForElt = !cast<ConstantInt>(C)->isZero();
+
+ // State machine for single/double/range index comparison.
+ if (IsTrueForElt) {
+ // Update the TrueElement state machine.
+ if (FirstTrueElement == Undefined)
+ FirstTrueElement = TrueRangeEnd = i; // First true element.
+ else {
+ // Update double-compare state machine.
+ if (SecondTrueElement == Undefined)
+ SecondTrueElement = i;
+ else
+ SecondTrueElement = Overdefined;
+
+ // Update range state machine.
+ if (TrueRangeEnd == (int)i-1)
+ TrueRangeEnd = i;
+ else
+ TrueRangeEnd = Overdefined;
+ }
+ } else {
+ // Update the FalseElement state machine.
+ if (FirstFalseElement == Undefined)
+ FirstFalseElement = FalseRangeEnd = i; // First false element.
+ else {
+ // Update double-compare state machine.
+ if (SecondFalseElement == Undefined)
+ SecondFalseElement = i;
+ else
+ SecondFalseElement = Overdefined;
+
+ // Update range state machine.
+ if (FalseRangeEnd == (int)i-1)
+ FalseRangeEnd = i;
+ else
+ FalseRangeEnd = Overdefined;
+ }
+ }
+
+
+ // If this element is in range, update our magic bitvector.
+ if (i < 64 && IsTrueForElt)
+ MagicBitvector |= 1ULL << i;
+
+ // If all of our states become overdefined, bail out early. Since the
+ // predicate is expensive, only check it every 8 elements. This is only
+ // really useful for really huge arrays.
+ if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined &&
+ SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined &&
+ FalseRangeEnd == Overdefined)
+ return 0;
+ }
+
+ // Now that we've scanned the entire array, emit our new comparison(s). We
+ // order the state machines in complexity of the generated code.
+ Value *Idx = GEP->getOperand(2);
+
+
+ // If the comparison is only true for one or two elements, emit direct
+ // comparisons.
+ if (SecondTrueElement != Overdefined) {
+ // None true -> false.
+ if (FirstTrueElement == Undefined)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
+
+ Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement);
+
+ // True for one element -> 'i == 47'.
+ if (SecondTrueElement == Undefined)
+ return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx);
+
+ // True for two elements -> 'i == 47 | i == 72'.
+ Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx);
+ Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement);
+ Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx);
+ return BinaryOperator::CreateOr(C1, C2);
+ }
+
+ // If the comparison is only false for one or two elements, emit direct
+ // comparisons.
+ if (SecondFalseElement != Overdefined) {
+ // None false -> true.
+ if (FirstFalseElement == Undefined)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
+
+ Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement);
+
+ // False for one element -> 'i != 47'.
+ if (SecondFalseElement == Undefined)
+ return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx);
+
+ // False for two elements -> 'i != 47 & i != 72'.
+ Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx);
+ Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement);
+ Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx);
+ return BinaryOperator::CreateAnd(C1, C2);
+ }
+
+ // If the comparison can be replaced with a range comparison for the elements
+ // where it is true, emit the range check.
+ if (TrueRangeEnd != Overdefined) {
+ assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare");
+
+ // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1).
+ if (FirstTrueElement) {
+ Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement);
+ Idx = Builder->CreateAdd(Idx, Offs);
+ }
+
+ Value *End = ConstantInt::get(Idx->getType(),
+ TrueRangeEnd-FirstTrueElement+1);
+ return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End);
+ }
+
+ // False range check.
+ if (FalseRangeEnd != Overdefined) {
+ assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare");
+ // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse).
+ if (FirstFalseElement) {
+ Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement);
+ Idx = Builder->CreateAdd(Idx, Offs);
+ }
+
+ Value *End = ConstantInt::get(Idx->getType(),
+ FalseRangeEnd-FirstFalseElement);
+ return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End);
+ }
+
+
+ // If a 32-bit or 64-bit magic bitvector captures the entire comparison state
+ // of this load, replace it with computation that does:
+ // ((magic_cst >> i) & 1) != 0
+ if (Init->getNumOperands() <= 32 ||
+ (TD && Init->getNumOperands() <= 64 && TD->isLegalInteger(64))) {
+ const Type *Ty;
+ if (Init->getNumOperands() <= 32)
+ Ty = Type::getInt32Ty(Init->getContext());
+ else
+ Ty = Type::getInt64Ty(Init->getContext());
+ Value *V = Builder->CreateIntCast(Idx, Ty, false);
+ V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V);
+ V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V);
+ return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0));
+ }
+
+ return 0;
+}
+
+
+Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
+ bool Changed = false;
+
+ /// Orders the operands of the compare so that they are listed from most
+ /// complex to least complex. This puts constants before unary operators,
+ /// before binary operators.
+ if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
+ I.swapOperands();
+ Changed = true;
+ }
+
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Value *V = SimplifyFCmpInst(I.getPredicate(), Op0, Op1, TD))
+ return ReplaceInstUsesWith(I, V);
+
+ // Simplify 'fcmp pred X, X'
+ if (Op0 == Op1) {
+ switch (I.getPredicate()) {
+ default: llvm_unreachable("Unknown predicate!");
+ case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
+ case FCmpInst::FCMP_ULT: // True if unordered or less than
+ case FCmpInst::FCMP_UGT: // True if unordered or greater than
+ case FCmpInst::FCMP_UNE: // True if unordered or not equal
+ // Canonicalize these to be 'fcmp uno %X, 0.0'.
+ I.setPredicate(FCmpInst::FCMP_UNO);
+ I.setOperand(1, Constant::getNullValue(Op0->getType()));
+ return &I;
+
+ case FCmpInst::FCMP_ORD: // True if ordered (no nans)
+ case FCmpInst::FCMP_OEQ: // True if ordered and equal
+ case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
+ case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
+ // Canonicalize these to be 'fcmp ord %X, 0.0'.
+ I.setPredicate(FCmpInst::FCMP_ORD);
+ I.setOperand(1, Constant::getNullValue(Op0->getType()));
+ return &I;
+ }
+ }
+
+ // Handle fcmp with constant RHS
+ if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
+ if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
+ switch (LHSI->getOpcode()) {
+ case Instruction::PHI:
+ // Only fold fcmp into the PHI if the phi and fcmp are in the same
+ // block. If in the same block, we're encouraging jump threading. If
+ // not, we are just pessimizing the code by making an i1 phi.
+ if (LHSI->getParent() == I.getParent())
+ if (Instruction *NV = FoldOpIntoPhi(I, true))
+ return NV;
+ break;
+ case Instruction::SIToFP:
+ case Instruction::UIToFP:
+ if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC))
+ return NV;
+ break;
+ case Instruction::Select: {
+ // If either operand of the select is a constant, we can fold the
+ // comparison into the select arms, which will cause one to be
+ // constant folded and the select turned into a bitwise or.
+ Value *Op1 = 0, *Op2 = 0;
+ if (LHSI->hasOneUse()) {
+ if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
+ // Fold the known value into the constant operand.
+ Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
+ // Insert a new FCmp of the other select operand.
+ Op2 = Builder->CreateFCmp(I.getPredicate(),
+ LHSI->getOperand(2), RHSC, I.getName());
+ } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
+ // Fold the known value into the constant operand.
+ Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
+ // Insert a new FCmp of the other select operand.
+ Op1 = Builder->CreateFCmp(I.getPredicate(), LHSI->getOperand(1),
+ RHSC, I.getName());
+ }
+ }
+
+ if (Op1)
+ return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
+ break;
+ }
+ case Instruction::Load:
+ if (GetElementPtrInst *GEP =
+ dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
+ if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
+ !cast<LoadInst>(LHSI)->isVolatile())
+ if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
+ return Res;
+ }
+ break;
+ }
+ }
+
+ return Changed ? &I : 0;
+}
+
+Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
+ bool Changed = false;
+
+ /// Orders the operands of the compare so that they are listed from most
+ /// complex to least complex. This puts constants before unary operators,
+ /// before binary operators.
+ if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
+ I.swapOperands();
+ Changed = true;
+ }
+
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, TD))
+ return ReplaceInstUsesWith(I, V);
+
+ const Type *Ty = Op0->getType();
+
+ // icmp's with boolean values can always be turned into bitwise operations
+ if (Ty == Type::getInt1Ty(*Context)) {
+ switch (I.getPredicate()) {
+ default: llvm_unreachable("Invalid icmp instruction!");
+ case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B)
+ Value *Xor = Builder->CreateXor(Op0, Op1, I.getName()+"tmp");
+ return BinaryOperator::CreateNot(Xor);
+ }
+ case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B
+ return BinaryOperator::CreateXor(Op0, Op1);
+
+ case ICmpInst::ICMP_UGT:
+ std::swap(Op0, Op1); // Change icmp ugt -> icmp ult
+ // FALL THROUGH
+ case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B
+ Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
+ return BinaryOperator::CreateAnd(Not, Op1);
+ }
+ case ICmpInst::ICMP_SGT:
+ std::swap(Op0, Op1); // Change icmp sgt -> icmp slt
+ // FALL THROUGH
+ case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B
+ Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
+ return BinaryOperator::CreateAnd(Not, Op0);
+ }
+ case ICmpInst::ICMP_UGE:
+ std::swap(Op0, Op1); // Change icmp uge -> icmp ule
+ // FALL THROUGH
+ case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B
+ Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
+ return BinaryOperator::CreateOr(Not, Op1);
+ }
+ case ICmpInst::ICMP_SGE:
+ std::swap(Op0, Op1); // Change icmp sge -> icmp sle
+ // FALL THROUGH
+ case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B
+ Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
+ return BinaryOperator::CreateOr(Not, Op0);
+ }
+ }
+ }
+
+ unsigned BitWidth = 0;
+ if (TD)
+ BitWidth = TD->getTypeSizeInBits(Ty->getScalarType());
+ else if (Ty->isIntOrIntVector())
+ BitWidth = Ty->getScalarSizeInBits();
+
+ bool isSignBit = false;
+
+ // See if we are doing a comparison with a constant.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ Value *A = 0, *B = 0;
+
+ // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B)
+ if (I.isEquality() && CI->isZero() &&
+ match(Op0, m_Sub(m_Value(A), m_Value(B)))) {
+ // (icmp cond A B) if cond is equality
+ return new ICmpInst(I.getPredicate(), A, B);
+ }
+
+ // If we have an icmp le or icmp ge instruction, turn it into the
+ // appropriate icmp lt or icmp gt instruction. This allows us to rely on
+ // them being folded in the code below. The SimplifyICmpInst code has
+ // already handled the edge cases for us, so we just assert on them.
+ switch (I.getPredicate()) {
+ default: break;
+ case ICmpInst::ICMP_ULE:
+ assert(!CI->isMaxValue(false)); // A <=u MAX -> TRUE
+ return new ICmpInst(ICmpInst::ICMP_ULT, Op0,
+ AddOne(CI));
+ case ICmpInst::ICMP_SLE:
+ assert(!CI->isMaxValue(true)); // A <=s MAX -> TRUE
+ return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
+ AddOne(CI));
+ case ICmpInst::ICMP_UGE:
+ assert(!CI->isMinValue(false)); // A >=u MIN -> TRUE
+ return new ICmpInst(ICmpInst::ICMP_UGT, Op0,
+ SubOne(CI));
+ case ICmpInst::ICMP_SGE:
+ assert(!CI->isMinValue(true)); // A >=s MIN -> TRUE
+ return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
+ SubOne(CI));
+ }
+
+ // If this comparison is a normal comparison, it demands all
+ // bits, if it is a sign bit comparison, it only demands the sign bit.
+ bool UnusedBit;
+ isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
+ }
+
+ // See if we can fold the comparison based on range information we can get
+ // by checking whether bits are known to be zero or one in the input.
+ if (BitWidth != 0) {
+ APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0);
+ APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0);
+
+ if (SimplifyDemandedBits(I.getOperandUse(0),
+ isSignBit ? APInt::getSignBit(BitWidth)
+ : APInt::getAllOnesValue(BitWidth),
+ Op0KnownZero, Op0KnownOne, 0))
+ return &I;
+ if (SimplifyDemandedBits(I.getOperandUse(1),
+ APInt::getAllOnesValue(BitWidth),
+ Op1KnownZero, Op1KnownOne, 0))
+ return &I;
+
+ // Given the known and unknown bits, compute a range that the LHS could be
+ // in. Compute the Min, Max and RHS values based on the known bits. For the
+ // EQ and NE we use unsigned values.
+ APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0);
+ APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0);
+ if (I.isSigned()) {
+ ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
+ Op0Min, Op0Max);
+ ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
+ Op1Min, Op1Max);
+ } else {
+ ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
+ Op0Min, Op0Max);
+ ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
+ Op1Min, Op1Max);
+ }
+
+ // If Min and Max are known to be the same, then SimplifyDemandedBits
+ // figured out that the LHS is a constant. Just constant fold this now so
+ // that code below can assume that Min != Max.
+ if (!isa<Constant>(Op0) && Op0Min == Op0Max)
+ return new ICmpInst(I.getPredicate(),
+ ConstantInt::get(*Context, Op0Min), Op1);
+ if (!isa<Constant>(Op1) && Op1Min == Op1Max)
+ return new ICmpInst(I.getPredicate(), Op0,
+ ConstantInt::get(*Context, Op1Min));
+
+ // Based on the range information we know about the LHS, see if we can
+ // simplify this comparison. For example, (x&4) < 8 is always true.
+ switch (I.getPredicate()) {
+ default: llvm_unreachable("Unknown icmp opcode!");
+ case ICmpInst::ICMP_EQ:
+ if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ break;
+ case ICmpInst::ICMP_NE:
+ if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ break;
+ case ICmpInst::ICMP_ULT:
+ if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B)
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ if (Op1Max == Op0Min+1) // A <u C -> A == C-1 if min(A)+1 == C
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
+ SubOne(CI));
+
+ // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
+ if (CI->isMinValue(true))
+ return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
+ Constant::getAllOnesValue(Op0->getType()));
+ }
+ break;
+ case ICmpInst::ICMP_UGT:
+ if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+
+ if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B)
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ if (Op1Min == Op0Max-1) // A >u C -> A == C+1 if max(a)-1 == C
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
+ AddOne(CI));
+
+ // (x >u 2147483647) -> (x <s 0) -> true if sign bit set
+ if (CI->isMaxValue(true))
+ return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
+ Constant::getNullValue(Op0->getType()));
+ }
+ break;
+ case ICmpInst::ICMP_SLT:
+ if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B)
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ if (Op1Max == Op0Min+1) // A <s C -> A == C-1 if min(A)+1 == C
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
+ SubOne(CI));
+ }
+ break;
+ case ICmpInst::ICMP_SGT:
+ if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+
+ if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B)
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ if (Op1Min == Op0Max-1) // A >s C -> A == C+1 if max(A)-1 == C
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
+ AddOne(CI));
+ }
+ break;
+ case ICmpInst::ICMP_SGE:
+ assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!");
+ if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ break;
+ case ICmpInst::ICMP_SLE:
+ assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!");
+ if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ break;
+ case ICmpInst::ICMP_UGE:
+ assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!");
+ if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ break;
+ case ICmpInst::ICMP_ULE:
+ assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!");
+ if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
+ if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
+ break;
+ }
+
+ // Turn a signed comparison into an unsigned one if both operands
+ // are known to have the same sign.
+ if (I.isSigned() &&
+ ((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) ||
+ (Op0KnownOne.isNegative() && Op1KnownOne.isNegative())))
+ return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
+ }
+
+ // Test if the ICmpInst instruction is used exclusively by a select as
+ // part of a minimum or maximum operation. If so, refrain from doing
+ // any other folding. This helps out other analyses which understand
+ // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
+ // and CodeGen. And in this case, at least one of the comparison
+ // operands has at least one user besides the compare (the select),
+ // which would often largely negate the benefit of folding anyway.
+ if (I.hasOneUse())
+ if (SelectInst *SI = dyn_cast<SelectInst>(*I.use_begin()))
+ if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
+ (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
+ return 0;
+
+ // See if we are doing a comparison between a constant and an instruction that
+ // can be folded into the comparison.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ // Since the RHS is a ConstantInt (CI), if the left hand side is an
+ // instruction, see if that instruction also has constants so that the
+ // instruction can be folded into the icmp
+ if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
+ if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
+ return Res;
+ }
+
+ // Handle icmp with constant (but not simple integer constant) RHS
+ if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
+ if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
+ switch (LHSI->getOpcode()) {
+ case Instruction::GetElementPtr:
+ // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
+ if (RHSC->isNullValue() &&
+ cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices())
+ return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
+ Constant::getNullValue(LHSI->getOperand(0)->getType()));
+ break;
+ case Instruction::PHI:
+ // Only fold icmp into the PHI if the phi and icmp are in the same
+ // block. If in the same block, we're encouraging jump threading. If
+ // not, we are just pessimizing the code by making an i1 phi.
+ if (LHSI->getParent() == I.getParent())
+ if (Instruction *NV = FoldOpIntoPhi(I, true))
+ return NV;
+ break;
+ case Instruction::Select: {
+ // If either operand of the select is a constant, we can fold the
+ // comparison into the select arms, which will cause one to be
+ // constant folded and the select turned into a bitwise or.
+ Value *Op1 = 0, *Op2 = 0;
+ if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1)))
+ Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
+ if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2)))
+ Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
+
+ // We only want to perform this transformation if it will not lead to
+ // additional code. This is true if either both sides of the select
+ // fold to a constant (in which case the icmp is replaced with a select
+ // which will usually simplify) or this is the only user of the
+ // select (in which case we are trading a select+icmp for a simpler
+ // select+icmp).
+ if ((Op1 && Op2) || (LHSI->hasOneUse() && (Op1 || Op2))) {
+ if (!Op1)
+ Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1),
+ RHSC, I.getName());
+ if (!Op2)
+ Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2),
+ RHSC, I.getName());
+ return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
+ }
+ break;
+ }
+ case Instruction::Call:
+ // If we have (malloc != null), and if the malloc has a single use, we
+ // can assume it is successful and remove the malloc.
+ if (isMalloc(LHSI) && LHSI->hasOneUse() &&
+ isa<ConstantPointerNull>(RHSC)) {
+ // Need to explicitly erase malloc call here, instead of adding it to
+ // Worklist, because it won't get DCE'd from the Worklist since
+ // isInstructionTriviallyDead() returns false for function calls.
+ // It is OK to replace LHSI/MallocCall with Undef because the
+ // instruction that uses it will be erased via Worklist.
+ if (extractMallocCall(LHSI)) {
+ LHSI->replaceAllUsesWith(UndefValue::get(LHSI->getType()));
+ EraseInstFromFunction(*LHSI);
+ return ReplaceInstUsesWith(I,
+ ConstantInt::get(Type::getInt1Ty(*Context),
+ !I.isTrueWhenEqual()));
+ }
+ if (CallInst* MallocCall = extractMallocCallFromBitCast(LHSI))
+ if (MallocCall->hasOneUse()) {
+ MallocCall->replaceAllUsesWith(
+ UndefValue::get(MallocCall->getType()));
+ EraseInstFromFunction(*MallocCall);
+ Worklist.Add(LHSI); // The malloc's bitcast use.
+ return ReplaceInstUsesWith(I,
+ ConstantInt::get(Type::getInt1Ty(*Context),
+ !I.isTrueWhenEqual()));
+ }
+ }
+ break;
+ case Instruction::IntToPtr:
+ // icmp pred inttoptr(X), null -> icmp pred X, 0
+ if (RHSC->isNullValue() && TD &&
+ TD->getIntPtrType(RHSC->getContext()) ==
+ LHSI->getOperand(0)->getType())
+ return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
+ Constant::getNullValue(LHSI->getOperand(0)->getType()));
+ break;
+
+ case Instruction::Load:
+ // Try to optimize things like "A[i] > 4" to index computations.
+ if (GetElementPtrInst *GEP =
+ dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
+ if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
+ !cast<LoadInst>(LHSI)->isVolatile())
+ if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
+ return Res;
+ }
+ break;
+ }
+ }
+
+ // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
+ if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0))
+ if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
+ return NI;
+ if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1))
+ if (Instruction *NI = FoldGEPICmp(GEP, Op0,
+ ICmpInst::getSwappedPredicate(I.getPredicate()), I))
+ return NI;
+
+ // Test to see if the operands of the icmp are casted versions of other
+ // values. If the ptr->ptr cast can be stripped off both arguments, we do so
+ // now.
+ if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
+ if (isa<PointerType>(Op0->getType()) &&
+ (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
+ // We keep moving the cast from the left operand over to the right
+ // operand, where it can often be eliminated completely.
+ Op0 = CI->getOperand(0);
+
+ // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
+ // so eliminate it as well.
+ if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
+ Op1 = CI2->getOperand(0);
+
+ // If Op1 is a constant, we can fold the cast into the constant.
+ if (Op0->getType() != Op1->getType()) {
+ if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
+ Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
+ } else {
+ // Otherwise, cast the RHS right before the icmp
+ Op1 = Builder->CreateBitCast(Op1, Op0->getType());
+ }
+ }
+ return new ICmpInst(I.getPredicate(), Op0, Op1);
+ }
+ }
+
+ if (isa<CastInst>(Op0)) {
+ // Handle the special case of: icmp (cast bool to X), <cst>
+ // This comes up when you have code like
+ // int X = A < B;
+ // if (X) ...
+ // For generality, we handle any zero-extension of any operand comparison
+ // with a constant or another cast from the same type.
+ if (isa<Constant>(Op1) || isa<CastInst>(Op1))
+ if (Instruction *R = visitICmpInstWithCastAndCast(I))
+ return R;
+ }
+
+ // See if it's the same type of instruction on the left and right.
+ if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
+ if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
+ if (Op0I->getOpcode() == Op1I->getOpcode() && Op0I->hasOneUse() &&
+ Op1I->hasOneUse() && Op0I->getOperand(1) == Op1I->getOperand(1)) {
+ switch (Op0I->getOpcode()) {
+ default: break;
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Xor:
+ if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
+ return new ICmpInst(I.getPredicate(), Op0I->getOperand(0),
+ Op1I->getOperand(0));
+ // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
+ if (CI->getValue().isSignBit()) {
+ ICmpInst::Predicate Pred = I.isSigned()
+ ? I.getUnsignedPredicate()
+ : I.getSignedPredicate();
+ return new ICmpInst(Pred, Op0I->getOperand(0),
+ Op1I->getOperand(0));
+ }
+
+ if (CI->getValue().isMaxSignedValue()) {
+ ICmpInst::Predicate Pred = I.isSigned()
+ ? I.getUnsignedPredicate()
+ : I.getSignedPredicate();
+ Pred = I.getSwappedPredicate(Pred);
+ return new ICmpInst(Pred, Op0I->getOperand(0),
+ Op1I->getOperand(0));
+ }
+ }
+ break;
+ case Instruction::Mul:
+ if (!I.isEquality())
+ break;
+
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
+ // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask
+ // Mask = -1 >> count-trailing-zeros(Cst).
+ if (!CI->isZero() && !CI->isOne()) {
+ const APInt &AP = CI->getValue();
+ ConstantInt *Mask = ConstantInt::get(*Context,
+ APInt::getLowBitsSet(AP.getBitWidth(),
+ AP.getBitWidth() -
+ AP.countTrailingZeros()));
+ Value *And1 = Builder->CreateAnd(Op0I->getOperand(0), Mask);
+ Value *And2 = Builder->CreateAnd(Op1I->getOperand(0), Mask);
+ return new ICmpInst(I.getPredicate(), And1, And2);
+ }
+ }
+ break;
+ }
+ }
+ }
+ }
+
+ // ~x < ~y --> y < x
+ { Value *A, *B;
+ if (match(Op0, m_Not(m_Value(A))) &&
+ match(Op1, m_Not(m_Value(B))))
+ return new ICmpInst(I.getPredicate(), B, A);
+ }
+
+ if (I.isEquality()) {
+ Value *A, *B, *C, *D;
+
+ // -x == -y --> x == y
+ if (match(Op0, m_Neg(m_Value(A))) &&
+ match(Op1, m_Neg(m_Value(B))))
+ return new ICmpInst(I.getPredicate(), A, B);
+
+ if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
+ if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
+ Value *OtherVal = A == Op1 ? B : A;
+ return new ICmpInst(I.getPredicate(), OtherVal,
+ Constant::getNullValue(A->getType()));
+ }
+
+ if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
+ // A^c1 == C^c2 --> A == C^(c1^c2)
+ ConstantInt *C1, *C2;
+ if (match(B, m_ConstantInt(C1)) &&
+ match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) {
+ Constant *NC =
+ ConstantInt::get(*Context, C1->getValue() ^ C2->getValue());
+ Value *Xor = Builder->CreateXor(C, NC, "tmp");
+ return new ICmpInst(I.getPredicate(), A, Xor);
+ }
+
+ // A^B == A^D -> B == D
+ if (A == C) return new ICmpInst(I.getPredicate(), B, D);
+ if (A == D) return new ICmpInst(I.getPredicate(), B, C);
+ if (B == C) return new ICmpInst(I.getPredicate(), A, D);
+ if (B == D) return new ICmpInst(I.getPredicate(), A, C);
+ }
+ }
+
+ if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
+ (A == Op0 || B == Op0)) {
+ // A == (A^B) -> B == 0
+ Value *OtherVal = A == Op0 ? B : A;
+ return new ICmpInst(I.getPredicate(), OtherVal,
+ Constant::getNullValue(A->getType()));
+ }
+
+ // (A-B) == A -> B == 0
+ if (match(Op0, m_Sub(m_Specific(Op1), m_Value(B))))
+ return new ICmpInst(I.getPredicate(), B,
+ Constant::getNullValue(B->getType()));
+
+ // A == (A-B) -> B == 0
+ if (match(Op1, m_Sub(m_Specific(Op0), m_Value(B))))
+ return new ICmpInst(I.getPredicate(), B,
+ Constant::getNullValue(B->getType()));
+
+ // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
+ if (Op0->hasOneUse() && Op1->hasOneUse() &&
+ match(Op0, m_And(m_Value(A), m_Value(B))) &&
+ match(Op1, m_And(m_Value(C), m_Value(D)))) {
+ Value *X = 0, *Y = 0, *Z = 0;
+
+ if (A == C) {
+ X = B; Y = D; Z = A;
+ } else if (A == D) {
+ X = B; Y = C; Z = A;
+ } else if (B == C) {
+ X = A; Y = D; Z = B;
+ } else if (B == D) {
+ X = A; Y = C; Z = B;
+ }
+
+ if (X) { // Build (X^Y) & Z
+ Op1 = Builder->CreateXor(X, Y, "tmp");
+ Op1 = Builder->CreateAnd(Op1, Z, "tmp");
+ I.setOperand(0, Op1);
+ I.setOperand(1, Constant::getNullValue(Op1->getType()));
+ return &I;
+ }
+ }
+ }
+
+ {
+ Value *X; ConstantInt *Cst;
+ // icmp X+Cst, X
+ if (match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op1 == X)
+ return FoldICmpAddOpCst(I, X, Cst, I.getPredicate(), Op0);
+
+ // icmp X, X+Cst
+ if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X)
+ return FoldICmpAddOpCst(I, X, Cst, I.getSwappedPredicate(), Op1);
+ }
+ return Changed ? &I : 0;
+}
+
+/// FoldICmpAddOpCst - Fold "icmp pred (X+CI), X".
+Instruction *InstCombiner::FoldICmpAddOpCst(ICmpInst &ICI,
+ Value *X, ConstantInt *CI,
+ ICmpInst::Predicate Pred,
+ Value *TheAdd) {
+ // If we have X+0, exit early (simplifying logic below) and let it get folded
+ // elsewhere. icmp X+0, X -> icmp X, X
+ if (CI->isZero()) {
+ bool isTrue = ICmpInst::isTrueWhenEqual(Pred);
+ return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
+ }
+
+ // (X+4) == X -> false.
+ if (Pred == ICmpInst::ICMP_EQ)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext()));
+
+ // (X+4) != X -> true.
+ if (Pred == ICmpInst::ICMP_NE)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext()));
+
+ // If this is an instruction (as opposed to constantexpr) get NUW/NSW info.
+ bool isNUW = false, isNSW = false;
+ if (BinaryOperator *Add = dyn_cast<BinaryOperator>(TheAdd)) {
+ isNUW = Add->hasNoUnsignedWrap();
+ isNSW = Add->hasNoSignedWrap();
+ }
+
+ // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0,
+ // so the values can never be equal. Similiarly for all other "or equals"
+ // operators.
+
+ // (X+1) <u X --> X >u (MAXUINT-1) --> X != 255
+ // (X+2) <u X --> X >u (MAXUINT-2) --> X > 253
+ // (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0
+ if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) {
+ // If this is an NUW add, then this is always false.
+ if (isNUW)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext()));
+
+ Value *R = ConstantExpr::getSub(ConstantInt::get(CI->getType(), -1ULL), CI);
+ return new ICmpInst(ICmpInst::ICMP_UGT, X, R);
+ }
+
+ // (X+1) >u X --> X <u (0-1) --> X != 255
+ // (X+2) >u X --> X <u (0-2) --> X <u 254
+ // (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0
+ if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) {
+ // If this is an NUW add, then this is always true.
+ if (isNUW)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext()));
+ return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantExpr::getNeg(CI));
+ }
+
+ unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits();
+ ConstantInt *SMax = ConstantInt::get(X->getContext(),
+ APInt::getSignedMaxValue(BitWidth));
+
+ // (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127
+ // (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125
+ // (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0
+ // (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1
+ // (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126
+ // (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127
+ if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) {
+ // If this is an NSW add, then we have two cases: if the constant is
+ // positive, then this is always false, if negative, this is always true.
+ if (isNSW) {
+ bool isTrue = CI->getValue().isNegative();
+ return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
+ }
+
+ return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI));
+ }
+
+ // (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127
+ // (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126
+ // (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1
+ // (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2
+ // (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126
+ // (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128
+
+ // If this is an NSW add, then we have two cases: if the constant is
+ // positive, then this is always true, if negative, this is always false.
+ if (isNSW) {
+ bool isTrue = !CI->getValue().isNegative();
+ return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
+ }
+
+ assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE);
+ Constant *C = ConstantInt::get(X->getContext(), CI->getValue()-1);
+ return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C));
+}
+
+/// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
+/// and CmpRHS are both known to be integer constants.
+Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
+ ConstantInt *DivRHS) {
+ ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
+ const APInt &CmpRHSV = CmpRHS->getValue();
+
+ // FIXME: If the operand types don't match the type of the divide
+ // then don't attempt this transform. The code below doesn't have the
+ // logic to deal with a signed divide and an unsigned compare (and
+ // vice versa). This is because (x /s C1) <s C2 produces different
+ // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
+ // (x /u C1) <u C2. Simply casting the operands and result won't
+ // work. :( The if statement below tests that condition and bails
+ // if it finds it.
+ bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
+ if (!ICI.isEquality() && DivIsSigned != ICI.isSigned())
+ return 0;
+ if (DivRHS->isZero())
+ return 0; // The ProdOV computation fails on divide by zero.
+ if (DivIsSigned && DivRHS->isAllOnesValue())
+ return 0; // The overflow computation also screws up here
+ if (DivRHS->isOne())
+ return 0; // Not worth bothering, and eliminates some funny cases
+ // with INT_MIN.
+
+ // Compute Prod = CI * DivRHS. We are essentially solving an equation
+ // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
+ // C2 (CI). By solving for X we can turn this into a range check
+ // instead of computing a divide.
+ Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS);
+
+ // Determine if the product overflows by seeing if the product is
+ // not equal to the divide. Make sure we do the same kind of divide
+ // as in the LHS instruction that we're folding.
+ bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
+ ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
+
+ // Get the ICmp opcode
+ ICmpInst::Predicate Pred = ICI.getPredicate();
+
+ // Figure out the interval that is being checked. For example, a comparison
+ // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
+ // Compute this interval based on the constants involved and the signedness of
+ // the compare/divide. This computes a half-open interval, keeping track of
+ // whether either value in the interval overflows. After analysis each
+ // overflow variable is set to 0 if it's corresponding bound variable is valid
+ // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
+ int LoOverflow = 0, HiOverflow = 0;
+ Constant *LoBound = 0, *HiBound = 0;
+
+ if (!DivIsSigned) { // udiv
+ // e.g. X/5 op 3 --> [15, 20)
+ LoBound = Prod;
+ HiOverflow = LoOverflow = ProdOV;
+ if (!HiOverflow)
+ HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, Context, false);
+ } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0.
+ if (CmpRHSV == 0) { // (X / pos) op 0
+ // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
+ LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
+ HiBound = DivRHS;
+ } else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos
+ LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
+ HiOverflow = LoOverflow = ProdOV;
+ if (!HiOverflow)
+ HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, Context, true);
+ } else { // (X / pos) op neg
+ // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
+ HiBound = AddOne(Prod);
+ LoOverflow = HiOverflow = ProdOV ? -1 : 0;
+ if (!LoOverflow) {
+ ConstantInt* DivNeg =
+ cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
+ LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, Context,
+ true) ? -1 : 0;
+ }
+ }
+ } else if (DivRHS->getValue().isNegative()) { // Divisor is < 0.
+ if (CmpRHSV == 0) { // (X / neg) op 0
+ // e.g. X/-5 op 0 --> [-4, 5)
+ LoBound = AddOne(DivRHS);
+ HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
+ if (HiBound == DivRHS) { // -INTMIN = INTMIN
+ HiOverflow = 1; // [INTMIN+1, overflow)
+ HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN
+ }
+ } else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos
+ // e.g. X/-5 op 3 --> [-19, -14)
+ HiBound = AddOne(Prod);
+ HiOverflow = LoOverflow = ProdOV ? -1 : 0;
+ if (!LoOverflow)
+ LoOverflow = AddWithOverflow(LoBound, HiBound,
+ DivRHS, Context, true) ? -1 : 0;
+ } else { // (X / neg) op neg
+ LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20)
+ LoOverflow = HiOverflow = ProdOV;
+ if (!HiOverflow)
+ HiOverflow = SubWithOverflow(HiBound, Prod, DivRHS, Context, true);
+ }
+
+ // Dividing by a negative swaps the condition. LT <-> GT
+ Pred = ICmpInst::getSwappedPredicate(Pred);
+ }
+
+ Value *X = DivI->getOperand(0);
+ switch (Pred) {
+ default: llvm_unreachable("Unhandled icmp opcode!");
+ case ICmpInst::ICMP_EQ:
+ if (LoOverflow && HiOverflow)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
+ else if (HiOverflow)
+ return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
+ ICmpInst::ICMP_UGE, X, LoBound);
+ else if (LoOverflow)
+ return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
+ ICmpInst::ICMP_ULT, X, HiBound);
+ else
+ return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI);
+ case ICmpInst::ICMP_NE:
+ if (LoOverflow && HiOverflow)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
+ else if (HiOverflow)
+ return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
+ ICmpInst::ICMP_ULT, X, LoBound);
+ else if (LoOverflow)
+ return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
+ ICmpInst::ICMP_UGE, X, HiBound);
+ else
+ return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI);
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_SLT:
+ if (LoOverflow == +1) // Low bound is greater than input range.
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
+ if (LoOverflow == -1) // Low bound is less than input range.
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
+ return new ICmpInst(Pred, X, LoBound);
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_SGT:
+ if (HiOverflow == +1) // High bound greater than input range.
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
+ else if (HiOverflow == -1) // High bound less than input range.
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
+ if (Pred == ICmpInst::ICMP_UGT)
+ return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
+ else
+ return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
+ }
+}
+
+
+/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
+///
+Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
+ Instruction *LHSI,
+ ConstantInt *RHS) {
+ const APInt &RHSV = RHS->getValue();
+
+ switch (LHSI->getOpcode()) {
+ case Instruction::Trunc:
+ if (ICI.isEquality() && LHSI->hasOneUse()) {
+ // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
+ // of the high bits truncated out of x are known.
+ unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(),
+ SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits();
+ APInt Mask(APInt::getHighBitsSet(SrcBits, SrcBits-DstBits));
+ APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0);
+ ComputeMaskedBits(LHSI->getOperand(0), Mask, KnownZero, KnownOne);
+
+ // If all the high bits are known, we can do this xform.
+ if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) {
+ // Pull in the high bits from known-ones set.
+ APInt NewRHS(RHS->getValue());
+ NewRHS.zext(SrcBits);
+ NewRHS |= KnownOne;
+ return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
+ ConstantInt::get(*Context, NewRHS));
+ }
+ }
+ break;
+
+ case Instruction::Xor: // (icmp pred (xor X, XorCST), CI)
+ if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
+ // If this is a comparison that tests the signbit (X < 0) or (x > -1),
+ // fold the xor.
+ if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) ||
+ (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) {
+ Value *CompareVal = LHSI->getOperand(0);
+
+ // If the sign bit of the XorCST is not set, there is no change to
+ // the operation, just stop using the Xor.
+ if (!XorCST->getValue().isNegative()) {
+ ICI.setOperand(0, CompareVal);
+ Worklist.Add(LHSI);
+ return &ICI;
+ }
+
+ // Was the old condition true if the operand is positive?
+ bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
+
+ // If so, the new one isn't.
+ isTrueIfPositive ^= true;
+
+ if (isTrueIfPositive)
+ return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal,
+ SubOne(RHS));
+ else
+ return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal,
+ AddOne(RHS));
+ }
+
+ if (LHSI->hasOneUse()) {
+ // (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit))
+ if (!ICI.isEquality() && XorCST->getValue().isSignBit()) {
+ const APInt &SignBit = XorCST->getValue();
+ ICmpInst::Predicate Pred = ICI.isSigned()
+ ? ICI.getUnsignedPredicate()
+ : ICI.getSignedPredicate();
+ return new ICmpInst(Pred, LHSI->getOperand(0),
+ ConstantInt::get(*Context, RHSV ^ SignBit));
+ }
+
+ // (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A)
+ if (!ICI.isEquality() && XorCST->getValue().isMaxSignedValue()) {
+ const APInt &NotSignBit = XorCST->getValue();
+ ICmpInst::Predicate Pred = ICI.isSigned()
+ ? ICI.getUnsignedPredicate()
+ : ICI.getSignedPredicate();
+ Pred = ICI.getSwappedPredicate(Pred);
+ return new ICmpInst(Pred, LHSI->getOperand(0),
+ ConstantInt::get(*Context, RHSV ^ NotSignBit));
+ }
+ }
+ }
+ break;
+ case Instruction::And: // (icmp pred (and X, AndCST), RHS)
+ if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
+ LHSI->getOperand(0)->hasOneUse()) {
+ ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
+
+ // If the LHS is an AND of a truncating cast, we can widen the
+ // and/compare to be the input width without changing the value
+ // produced, eliminating a cast.
+ if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
+ // We can do this transformation if either the AND constant does not
+ // have its sign bit set or if it is an equality comparison.
+ // Extending a relational comparison when we're checking the sign
+ // bit would not work.
+ if (Cast->hasOneUse() &&
+ (ICI.isEquality() ||
+ (AndCST->getValue().isNonNegative() && RHSV.isNonNegative()))) {
+ uint32_t BitWidth =
+ cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth();
+ APInt NewCST = AndCST->getValue();
+ NewCST.zext(BitWidth);
+ APInt NewCI = RHSV;
+ NewCI.zext(BitWidth);
+ Value *NewAnd =
+ Builder->CreateAnd(Cast->getOperand(0),
+ ConstantInt::get(*Context, NewCST), LHSI->getName());
+ return new ICmpInst(ICI.getPredicate(), NewAnd,
+ ConstantInt::get(*Context, NewCI));
+ }
+ }
+
+ // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
+ // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
+ // happens a LOT in code produced by the C front-end, for bitfield
+ // access.
+ BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
+ if (Shift && !Shift->isShift())
+ Shift = 0;
+
+ ConstantInt *ShAmt;
+ ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0;
+ const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift.
+ const Type *AndTy = AndCST->getType(); // Type of the and.
+
+ // We can fold this as long as we can't shift unknown bits
+ // into the mask. This can only happen with signed shift
+ // rights, as they sign-extend.
+ if (ShAmt) {
+ bool CanFold = Shift->isLogicalShift();
+ if (!CanFold) {
+ // To test for the bad case of the signed shr, see if any
+ // of the bits shifted in could be tested after the mask.
+ uint32_t TyBits = Ty->getPrimitiveSizeInBits();
+ int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits);
+
+ uint32_t BitWidth = AndTy->getPrimitiveSizeInBits();
+ if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) &
+ AndCST->getValue()) == 0)
+ CanFold = true;
+ }
+
+ if (CanFold) {
+ Constant *NewCst;
+ if (Shift->getOpcode() == Instruction::Shl)
+ NewCst = ConstantExpr::getLShr(RHS, ShAmt);
+ else
+ NewCst = ConstantExpr::getShl(RHS, ShAmt);
+
+ // Check to see if we are shifting out any of the bits being
+ // compared.
+ if (ConstantExpr::get(Shift->getOpcode(),
+ NewCst, ShAmt) != RHS) {
+ // If we shifted bits out, the fold is not going to work out.
+ // As a special case, check to see if this means that the
+ // result is always true or false now.
+ if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
+ if (ICI.getPredicate() == ICmpInst::ICMP_NE)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
+ } else {
+ ICI.setOperand(1, NewCst);
+ Constant *NewAndCST;
+ if (Shift->getOpcode() == Instruction::Shl)
+ NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt);
+ else
+ NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
+ LHSI->setOperand(1, NewAndCST);
+ LHSI->setOperand(0, Shift->getOperand(0));
+ Worklist.Add(Shift); // Shift is dead.
+ return &ICI;
+ }
+ }
+ }
+
+ // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
+ // preferable because it allows the C<<Y expression to be hoisted out
+ // of a loop if Y is invariant and X is not.
+ if (Shift && Shift->hasOneUse() && RHSV == 0 &&
+ ICI.isEquality() && !Shift->isArithmeticShift() &&
+ !isa<Constant>(Shift->getOperand(0))) {
+ // Compute C << Y.
+ Value *NS;
+ if (Shift->getOpcode() == Instruction::LShr) {
+ NS = Builder->CreateShl(AndCST, Shift->getOperand(1), "tmp");
+ } else {
+ // Insert a logical shift.
+ NS = Builder->CreateLShr(AndCST, Shift->getOperand(1), "tmp");
+ }
+
+ // Compute X & (C << Y).
+ Value *NewAnd =
+ Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName());
+
+ ICI.setOperand(0, NewAnd);
+ return &ICI;
+ }
+ }
+
+ // Try to optimize things like "A[i]&42 == 0" to index computations.
+ if (LoadInst *LI = dyn_cast<LoadInst>(LHSI->getOperand(0))) {
+ if (GetElementPtrInst *GEP =
+ dyn_cast<GetElementPtrInst>(LI->getOperand(0)))
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
+ if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
+ !LI->isVolatile() && isa<ConstantInt>(LHSI->getOperand(1))) {
+ ConstantInt *C = cast<ConstantInt>(LHSI->getOperand(1));
+ if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV,ICI, C))
+ return Res;
+ }
+ }
+ break;
+
+ case Instruction::Or: {
+ if (!ICI.isEquality() || !RHS->isNullValue() || !LHSI->hasOneUse())
+ break;
+ Value *P, *Q;
+ if (match(LHSI, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) {
+ // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0
+ // -> and (icmp eq P, null), (icmp eq Q, null).
+
+ Value *ICIP = Builder->CreateICmp(ICI.getPredicate(), P,
+ Constant::getNullValue(P->getType()));
+ Value *ICIQ = Builder->CreateICmp(ICI.getPredicate(), Q,
+ Constant::getNullValue(Q->getType()));
+ Instruction *Op;
+ if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
+ Op = BinaryOperator::CreateAnd(ICIP, ICIQ);
+ else
+ Op = BinaryOperator::CreateOr(ICIP, ICIQ);
+ return Op;
+ }
+ break;
+ }
+
+ case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
+ ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+ if (!ShAmt) break;
+
+ uint32_t TypeBits = RHSV.getBitWidth();
+
+ // Check that the shift amount is in range. If not, don't perform
+ // undefined shifts. When the shift is visited it will be
+ // simplified.
+ if (ShAmt->uge(TypeBits))
+ break;
+
+ if (ICI.isEquality()) {
+ // If we are comparing against bits always shifted out, the
+ // comparison cannot succeed.
+ Constant *Comp =
+ ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt),
+ ShAmt);
+ if (Comp != RHS) {// Comparing against a bit that we know is zero.
+ bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+ Constant *Cst = ConstantInt::get(Type::getInt1Ty(*Context), IsICMP_NE);
+ return ReplaceInstUsesWith(ICI, Cst);
+ }
+
+ if (LHSI->hasOneUse()) {
+ // Otherwise strength reduce the shift into an and.
+ uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
+ Constant *Mask =
+ ConstantInt::get(*Context, APInt::getLowBitsSet(TypeBits,
+ TypeBits-ShAmtVal));
+
+ Value *And =
+ Builder->CreateAnd(LHSI->getOperand(0),Mask, LHSI->getName()+".mask");
+ return new ICmpInst(ICI.getPredicate(), And,
+ ConstantInt::get(*Context, RHSV.lshr(ShAmtVal)));
+ }
+ }
+
+ // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
+ bool TrueIfSigned = false;
+ if (LHSI->hasOneUse() &&
+ isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
+ // (X << 31) <s 0 --> (X&1) != 0
+ Constant *Mask = ConstantInt::get(*Context, APInt(TypeBits, 1) <<
+ (TypeBits-ShAmt->getZExtValue()-1));
+ Value *And =
+ Builder->CreateAnd(LHSI->getOperand(0), Mask, LHSI->getName()+".mask");
+ return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
+ And, Constant::getNullValue(And->getType()));
+ }
+ break;
+ }
+
+ case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
+ case Instruction::AShr: {
+ // Only handle equality comparisons of shift-by-constant.
+ ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+ if (!ShAmt || !ICI.isEquality()) break;
+
+ // Check that the shift amount is in range. If not, don't perform
+ // undefined shifts. When the shift is visited it will be
+ // simplified.
+ uint32_t TypeBits = RHSV.getBitWidth();
+ if (ShAmt->uge(TypeBits))
+ break;
+
+ uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
+
+ // If we are comparing against bits always shifted out, the
+ // comparison cannot succeed.
+ APInt Comp = RHSV << ShAmtVal;
+ if (LHSI->getOpcode() == Instruction::LShr)
+ Comp = Comp.lshr(ShAmtVal);
+ else
+ Comp = Comp.ashr(ShAmtVal);
+
+ if (Comp != RHSV) { // Comparing against a bit that we know is zero.
+ bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+ Constant *Cst = ConstantInt::get(Type::getInt1Ty(*Context), IsICMP_NE);
+ return ReplaceInstUsesWith(ICI, Cst);
+ }
+
+ // Otherwise, check to see if the bits shifted out are known to be zero.
+ // If so, we can compare against the unshifted value:
+ // (X & 4) >> 1 == 2 --> (X & 4) == 4.
+ if (LHSI->hasOneUse() &&
+ MaskedValueIsZero(LHSI->getOperand(0),
+ APInt::getLowBitsSet(Comp.getBitWidth(), ShAmtVal))) {
+ return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
+ ConstantExpr::getShl(RHS, ShAmt));
+ }
+
+ if (LHSI->hasOneUse()) {
+ // Otherwise strength reduce the shift into an and.
+ APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
+ Constant *Mask = ConstantInt::get(*Context, Val);
+
+ Value *And = Builder->CreateAnd(LHSI->getOperand(0),
+ Mask, LHSI->getName()+".mask");
+ return new ICmpInst(ICI.getPredicate(), And,
+ ConstantExpr::getShl(RHS, ShAmt));
+ }
+ break;
+ }
+
+ case Instruction::SDiv:
+ case Instruction::UDiv:
+ // Fold: icmp pred ([us]div X, C1), C2 -> range test
+ // Fold this div into the comparison, producing a range check.
+ // Determine, based on the divide type, what the range is being
+ // checked. If there is an overflow on the low or high side, remember
+ // it, otherwise compute the range [low, hi) bounding the new value.
+ // See: InsertRangeTest above for the kinds of replacements possible.
+ if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
+ if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
+ DivRHS))
+ return R;
+ break;
+
+ case Instruction::Add:
+ // Fold: icmp pred (add X, C1), C2
+ if (!ICI.isEquality()) {
+ ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+ if (!LHSC) break;
+ const APInt &LHSV = LHSC->getValue();
+
+ ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV)
+ .subtract(LHSV);
+
+ if (ICI.isSigned()) {
+ if (CR.getLower().isSignBit()) {
+ return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0),
+ ConstantInt::get(*Context, CR.getUpper()));
+ } else if (CR.getUpper().isSignBit()) {
+ return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0),
+ ConstantInt::get(*Context, CR.getLower()));
+ }
+ } else {
+ if (CR.getLower().isMinValue()) {
+ return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0),
+ ConstantInt::get(*Context, CR.getUpper()));
+ } else if (CR.getUpper().isMinValue()) {
+ return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0),
+ ConstantInt::get(*Context, CR.getLower()));
+ }
+ }
+ }
+ break;
+ }
+
+ // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
+ if (ICI.isEquality()) {
+ bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+
+ // If the first operand is (add|sub|and|or|xor|rem) with a constant, and
+ // the second operand is a constant, simplify a bit.
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
+ switch (BO->getOpcode()) {
+ case Instruction::SRem:
+ // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
+ if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
+ const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
+ if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) {
+ Value *NewRem =
+ Builder->CreateURem(BO->getOperand(0), BO->getOperand(1),
+ BO->getName());
+ return new ICmpInst(ICI.getPredicate(), NewRem,
+ Constant::getNullValue(BO->getType()));
+ }
+ }
+ break;
+ case Instruction::Add:
+ // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
+ if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
+ if (BO->hasOneUse())
+ return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+ ConstantExpr::getSub(RHS, BOp1C));
+ } else if (RHSV == 0) {
+ // Replace ((add A, B) != 0) with (A != -B) if A or B is
+ // efficiently invertible, or if the add has just this one use.
+ Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
+
+ if (Value *NegVal = dyn_castNegVal(BOp1))
+ return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
+ else if (Value *NegVal = dyn_castNegVal(BOp0))
+ return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
+ else if (BO->hasOneUse()) {
+ Value *Neg = Builder->CreateNeg(BOp1);
+ Neg->takeName(BO);
+ return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
+ }
+ }
+ break;
+ case Instruction::Xor:
+ // For the xor case, we can xor two constants together, eliminating
+ // the explicit xor.
+ if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
+ return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+ ConstantExpr::getXor(RHS, BOC));
+
+ // FALLTHROUGH
+ case Instruction::Sub:
+ // Replace (([sub|xor] A, B) != 0) with (A != B)
+ if (RHSV == 0)
+ return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+ BO->getOperand(1));
+ break;
+
+ case Instruction::Or:
+ // If bits are being or'd in that are not present in the constant we
+ // are comparing against, then the comparison could never succeed!
+ if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
+ Constant *NotCI = ConstantExpr::getNot(RHS);
+ if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
+ return ReplaceInstUsesWith(ICI,
+ ConstantInt::get(Type::getInt1Ty(*Context),
+ isICMP_NE));
+ }
+ break;
+
+ case Instruction::And:
+ if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
+ // If bits are being compared against that are and'd out, then the
+ // comparison can never succeed!
+ if ((RHSV & ~BOC->getValue()) != 0)
+ return ReplaceInstUsesWith(ICI,
+ ConstantInt::get(Type::getInt1Ty(*Context),
+ isICMP_NE));
+
+ // If we have ((X & C) == C), turn it into ((X & C) != 0).
+ if (RHS == BOC && RHSV.isPowerOf2())
+ return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
+ ICmpInst::ICMP_NE, LHSI,
+ Constant::getNullValue(RHS->getType()));
+
+ // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
+ if (BOC->getValue().isSignBit()) {
+ Value *X = BO->getOperand(0);
+ Constant *Zero = Constant::getNullValue(X->getType());
+ ICmpInst::Predicate pred = isICMP_NE ?
+ ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
+ return new ICmpInst(pred, X, Zero);
+ }
+
+ // ((X & ~7) == 0) --> X < 8
+ if (RHSV == 0 && isHighOnes(BOC)) {
+ Value *X = BO->getOperand(0);
+ Constant *NegX = ConstantExpr::getNeg(BOC);
+ ICmpInst::Predicate pred = isICMP_NE ?
+ ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
+ return new ICmpInst(pred, X, NegX);
+ }
+ }
+ default: break;
+ }
+ } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
+ // Handle icmp {eq|ne} <intrinsic>, intcst.
+ if (II->getIntrinsicID() == Intrinsic::bswap) {
+ Worklist.Add(II);
+ ICI.setOperand(0, II->getOperand(1));
+ ICI.setOperand(1, ConstantInt::get(*Context, RHSV.byteSwap()));
+ return &ICI;
+ }
+ }
+ }
+ return 0;
+}
+
+/// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
+/// We only handle extending casts so far.
+///
+Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
+ const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
+ Value *LHSCIOp = LHSCI->getOperand(0);
+ const Type *SrcTy = LHSCIOp->getType();
+ const Type *DestTy = LHSCI->getType();
+ Value *RHSCIOp;
+
+ // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
+ // integer type is the same size as the pointer type.
+ if (TD && LHSCI->getOpcode() == Instruction::PtrToInt &&
+ TD->getPointerSizeInBits() ==
+ cast<IntegerType>(DestTy)->getBitWidth()) {
+ Value *RHSOp = 0;
+ if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
+ RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
+ } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
+ RHSOp = RHSC->getOperand(0);
+ // If the pointer types don't match, insert a bitcast.
+ if (LHSCIOp->getType() != RHSOp->getType())
+ RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType());
+ }
+
+ if (RHSOp)
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
+ }
+
+ // The code below only handles extension cast instructions, so far.
+ // Enforce this.
+ if (LHSCI->getOpcode() != Instruction::ZExt &&
+ LHSCI->getOpcode() != Instruction::SExt)
+ return 0;
+
+ bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
+ bool isSignedCmp = ICI.isSigned();
+
+ if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
+ // Not an extension from the same type?
+ RHSCIOp = CI->getOperand(0);
+ if (RHSCIOp->getType() != LHSCIOp->getType())
+ return 0;
+
+ // If the signedness of the two casts doesn't agree (i.e. one is a sext
+ // and the other is a zext), then we can't handle this.
+ if (CI->getOpcode() != LHSCI->getOpcode())
+ return 0;
+
+ // Deal with equality cases early.
+ if (ICI.isEquality())
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
+
+ // A signed comparison of sign extended values simplifies into a
+ // signed comparison.
+ if (isSignedCmp && isSignedExt)
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
+
+ // The other three cases all fold into an unsigned comparison.
+ return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
+ }
+
+ // If we aren't dealing with a constant on the RHS, exit early
+ ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
+ if (!CI)
+ return 0;
+
+ // Compute the constant that would happen if we truncated to SrcTy then
+ // reextended to DestTy.
+ Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
+ Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(),
+ Res1, DestTy);
+
+ // If the re-extended constant didn't change...
+ if (Res2 == CI) {
+ // Deal with equality cases early.
+ if (ICI.isEquality())
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
+
+ // A signed comparison of sign extended values simplifies into a
+ // signed comparison.
+ if (isSignedExt && isSignedCmp)
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
+
+ // The other three cases all fold into an unsigned comparison.
+ return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, Res1);
+ }
+
+ // The re-extended constant changed so the constant cannot be represented
+ // in the shorter type. Consequently, we cannot emit a simple comparison.
+
+ // First, handle some easy cases. We know the result cannot be equal at this
+ // point so handle the ICI.isEquality() cases
+ if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
+ if (ICI.getPredicate() == ICmpInst::ICMP_NE)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
+
+ // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
+ // should have been folded away previously and not enter in here.
+ Value *Result;
+ if (isSignedCmp) {
+ // We're performing a signed comparison.
+ if (cast<ConstantInt>(CI)->getValue().isNegative())
+ Result = ConstantInt::getFalse(*Context); // X < (small) --> false
+ else
+ Result = ConstantInt::getTrue(*Context); // X < (large) --> true
+ } else {
+ // We're performing an unsigned comparison.
+ if (isSignedExt) {
+ // We're performing an unsigned comp with a sign extended value.
+ // This is true if the input is >= 0. [aka >s -1]
+ Constant *NegOne = Constant::getAllOnesValue(SrcTy);
+ Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICI.getName());
+ } else {
+ // Unsigned extend & unsigned compare -> always true.
+ Result = ConstantInt::getTrue(*Context);
+ }
+ }
+
+ // Finally, return the value computed.
+ if (ICI.getPredicate() == ICmpInst::ICMP_ULT ||
+ ICI.getPredicate() == ICmpInst::ICMP_SLT)
+ return ReplaceInstUsesWith(ICI, Result);
+
+ assert((ICI.getPredicate()==ICmpInst::ICMP_UGT ||
+ ICI.getPredicate()==ICmpInst::ICMP_SGT) &&
+ "ICmp should be folded!");
+ if (Constant *CI = dyn_cast<Constant>(Result))
+ return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI));
+ return BinaryOperator::CreateNot(Result);
+}
+
+Instruction *InstCombiner::visitShl(BinaryOperator &I) {
+ return commonShiftTransforms(I);
+}
+
+Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
+ return commonShiftTransforms(I);
+}
+
+Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
+ if (Instruction *R = commonShiftTransforms(I))
+ return R;
+
+ Value *Op0 = I.getOperand(0);
+
+ // ashr int -1, X = -1 (for any arithmetic shift rights of ~0)
+ if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
+ if (CSI->isAllOnesValue())
+ return ReplaceInstUsesWith(I, CSI);
+
+ // See if we can turn a signed shr into an unsigned shr.
+ if (MaskedValueIsZero(Op0,
+ APInt::getSignBit(I.getType()->getScalarSizeInBits())))
+ return BinaryOperator::CreateLShr(Op0, I.getOperand(1));
+
+ // Arithmetic shifting an all-sign-bit value is a no-op.
+ unsigned NumSignBits = ComputeNumSignBits(Op0);
+ if (NumSignBits == Op0->getType()->getScalarSizeInBits())
+ return ReplaceInstUsesWith(I, Op0);
+
+ return 0;
+}
+
+Instruction *InstCombiner::commonShiftTransforms(BinaryOperator &I) {
+ assert(I.getOperand(1)->getType() == I.getOperand(0)->getType());
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // shl X, 0 == X and shr X, 0 == X
+ // shl 0, X == 0 and shr 0, X == 0
+ if (Op1 == Constant::getNullValue(Op1->getType()) ||
+ Op0 == Constant::getNullValue(Op0->getType()))
+ return ReplaceInstUsesWith(I, Op0);
+
+ if (isa<UndefValue>(Op0)) {
+ if (I.getOpcode() == Instruction::AShr) // undef >>s X -> undef
+ return ReplaceInstUsesWith(I, Op0);
+ else // undef << X -> 0, undef >>u X -> 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ }
+ if (isa<UndefValue>(Op1)) {
+ if (I.getOpcode() == Instruction::AShr) // X >>s undef -> X
+ return ReplaceInstUsesWith(I, Op0);
+ else // X << undef, X >>u undef -> 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ }
+
+ // See if we can fold away this shift.
+ if (SimplifyDemandedInstructionBits(I))
+ return &I;
+
+ // Try to fold constant and into select arguments.
+ if (isa<Constant>(Op0))
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+
+ if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op1))
+ if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
+ return Res;
+ return 0;
+}
+
+Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
+ BinaryOperator &I) {
+ bool isLeftShift = I.getOpcode() == Instruction::Shl;
+
+ // See if we can simplify any instructions used by the instruction whose sole
+ // purpose is to compute bits we don't care about.
+ uint32_t TypeBits = Op0->getType()->getScalarSizeInBits();
+
+ // shl i32 X, 32 = 0 and srl i8 Y, 9 = 0, ... just don't eliminate
+ // a signed shift.
+ //
+ if (Op1->uge(TypeBits)) {
+ if (I.getOpcode() != Instruction::AShr)
+ return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
+ else {
+ I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
+ return &I;
+ }
+ }
+
+ // ((X*C1) << C2) == (X * (C1 << C2))
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
+ if (BO->getOpcode() == Instruction::Mul && isLeftShift)
+ if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
+ return BinaryOperator::CreateMul(BO->getOperand(0),
+ ConstantExpr::getShl(BOOp, Op1));
+
+ // Try to fold constant and into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+
+ // Fold shift2(trunc(shift1(x,c1)), c2) -> trunc(shift2(shift1(x,c1),c2))
+ if (TruncInst *TI = dyn_cast<TruncInst>(Op0)) {
+ Instruction *TrOp = dyn_cast<Instruction>(TI->getOperand(0));
+ // If 'shift2' is an ashr, we would have to get the sign bit into a funny
+ // place. Don't try to do this transformation in this case. Also, we
+ // require that the input operand is a shift-by-constant so that we have
+ // confidence that the shifts will get folded together. We could do this
+ // xform in more cases, but it is unlikely to be profitable.
+ if (TrOp && I.isLogicalShift() && TrOp->isShift() &&
+ isa<ConstantInt>(TrOp->getOperand(1))) {
+ // Okay, we'll do this xform. Make the shift of shift.
+ Constant *ShAmt = ConstantExpr::getZExt(Op1, TrOp->getType());
+ // (shift2 (shift1 & 0x00FF), c2)
+ Value *NSh = Builder->CreateBinOp(I.getOpcode(), TrOp, ShAmt,I.getName());
+
+ // For logical shifts, the truncation has the effect of making the high
+ // part of the register be zeros. Emulate this by inserting an AND to
+ // clear the top bits as needed. This 'and' will usually be zapped by
+ // other xforms later if dead.
+ unsigned SrcSize = TrOp->getType()->getScalarSizeInBits();
+ unsigned DstSize = TI->getType()->getScalarSizeInBits();
+ APInt MaskV(APInt::getLowBitsSet(SrcSize, DstSize));
+
+ // The mask we constructed says what the trunc would do if occurring
+ // between the shifts. We want to know the effect *after* the second
+ // shift. We know that it is a logical shift by a constant, so adjust the
+ // mask as appropriate.
+ if (I.getOpcode() == Instruction::Shl)
+ MaskV <<= Op1->getZExtValue();
+ else {
+ assert(I.getOpcode() == Instruction::LShr && "Unknown logical shift");
+ MaskV = MaskV.lshr(Op1->getZExtValue());
+ }
+
+ // shift1 & 0x00FF
+ Value *And = Builder->CreateAnd(NSh, ConstantInt::get(*Context, MaskV),
+ TI->getName());
+
+ // Return the value truncated to the interesting size.
+ return new TruncInst(And, I.getType());
+ }
+ }
+
+ if (Op0->hasOneUse()) {
+ if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
+ // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
+ Value *V1, *V2;
+ ConstantInt *CC;
+ switch (Op0BO->getOpcode()) {
+ default: break;
+ case Instruction::Add:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor: {
+ // These operators commute.
+ // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
+ if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
+ match(Op0BO->getOperand(1), m_Shr(m_Value(V1),
+ m_Specific(Op1)))) {
+ Value *YS = // (Y << C)
+ Builder->CreateShl(Op0BO->getOperand(0), Op1, Op0BO->getName());
+ // (X + (Y << C))
+ Value *X = Builder->CreateBinOp(Op0BO->getOpcode(), YS, V1,
+ Op0BO->getOperand(1)->getName());
+ uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
+ return BinaryOperator::CreateAnd(X, ConstantInt::get(*Context,
+ APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
+ }
+
+ // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
+ Value *Op0BOOp1 = Op0BO->getOperand(1);
+ if (isLeftShift && Op0BOOp1->hasOneUse() &&
+ match(Op0BOOp1,
+ m_And(m_Shr(m_Value(V1), m_Specific(Op1)),
+ m_ConstantInt(CC))) &&
+ cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse()) {
+ Value *YS = // (Y << C)
+ Builder->CreateShl(Op0BO->getOperand(0), Op1,
+ Op0BO->getName());
+ // X & (CC << C)
+ Value *XM = Builder->CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
+ V1->getName()+".mask");
+ return BinaryOperator::Create(Op0BO->getOpcode(), YS, XM);
+ }
+ }
+
+ // FALL THROUGH.
+ case Instruction::Sub: {
+ // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
+ if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
+ match(Op0BO->getOperand(0), m_Shr(m_Value(V1),
+ m_Specific(Op1)))) {
+ Value *YS = // (Y << C)
+ Builder->CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
+ // (X + (Y << C))
+ Value *X = Builder->CreateBinOp(Op0BO->getOpcode(), V1, YS,
+ Op0BO->getOperand(0)->getName());
+ uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
+ return BinaryOperator::CreateAnd(X, ConstantInt::get(*Context,
+ APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
+ }
+
+ // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
+ if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
+ match(Op0BO->getOperand(0),
+ m_And(m_Shr(m_Value(V1), m_Value(V2)),
+ m_ConstantInt(CC))) && V2 == Op1 &&
+ cast<BinaryOperator>(Op0BO->getOperand(0))
+ ->getOperand(0)->hasOneUse()) {
+ Value *YS = // (Y << C)
+ Builder->CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
+ // X & (CC << C)
+ Value *XM = Builder->CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
+ V1->getName()+".mask");
+
+ return BinaryOperator::Create(Op0BO->getOpcode(), XM, YS);
+ }
+
+ break;
+ }
+ }
+
+
+ // If the operand is an bitwise operator with a constant RHS, and the
+ // shift is the only use, we can pull it out of the shift.
+ if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
+ bool isValid = true; // Valid only for And, Or, Xor
+ bool highBitSet = false; // Transform if high bit of constant set?
+
+ switch (Op0BO->getOpcode()) {
+ default: isValid = false; break; // Do not perform transform!
+ case Instruction::Add:
+ isValid = isLeftShift;
+ break;
+ case Instruction::Or:
+ case Instruction::Xor:
+ highBitSet = false;
+ break;
+ case Instruction::And:
+ highBitSet = true;
+ break;
+ }
+
+ // If this is a signed shift right, and the high bit is modified
+ // by the logical operation, do not perform the transformation.
+ // The highBitSet boolean indicates the value of the high bit of
+ // the constant which would cause it to be modified for this
+ // operation.
+ //
+ if (isValid && I.getOpcode() == Instruction::AShr)
+ isValid = Op0C->getValue()[TypeBits-1] == highBitSet;
+
+ if (isValid) {
+ Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
+
+ Value *NewShift =
+ Builder->CreateBinOp(I.getOpcode(), Op0BO->getOperand(0), Op1);
+ NewShift->takeName(Op0BO);
+
+ return BinaryOperator::Create(Op0BO->getOpcode(), NewShift,
+ NewRHS);
+ }
+ }
+ }
+ }
+
+ // Find out if this is a shift of a shift by a constant.
+ BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0);
+ if (ShiftOp && !ShiftOp->isShift())
+ ShiftOp = 0;
+
+ if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) {
+ ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1));
+ uint32_t ShiftAmt1 = ShiftAmt1C->getLimitedValue(TypeBits);
+ uint32_t ShiftAmt2 = Op1->getLimitedValue(TypeBits);
+ assert(ShiftAmt2 != 0 && "Should have been simplified earlier");
+ if (ShiftAmt1 == 0) return 0; // Will be simplified in the future.
+ Value *X = ShiftOp->getOperand(0);
+
+ uint32_t AmtSum = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
+
+ const IntegerType *Ty = cast<IntegerType>(I.getType());
+
+ // Check for (X << c1) << c2 and (X >> c1) >> c2
+ if (I.getOpcode() == ShiftOp->getOpcode()) {
+ // If this is oversized composite shift, then unsigned shifts get 0, ashr
+ // saturates.
+ if (AmtSum >= TypeBits) {
+ if (I.getOpcode() != Instruction::AShr)
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ AmtSum = TypeBits-1; // Saturate to 31 for i32 ashr.
+ }
+
+ return BinaryOperator::Create(I.getOpcode(), X,
+ ConstantInt::get(Ty, AmtSum));
+ }
+
+ if (ShiftOp->getOpcode() == Instruction::LShr &&
+ I.getOpcode() == Instruction::AShr) {
+ if (AmtSum >= TypeBits)
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ // ((X >>u C1) >>s C2) -> (X >>u (C1+C2)) since C1 != 0.
+ return BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, AmtSum));
+ }
+
+ if (ShiftOp->getOpcode() == Instruction::AShr &&
+ I.getOpcode() == Instruction::LShr) {
+ // ((X >>s C1) >>u C2) -> ((X >>s (C1+C2)) & mask) since C1 != 0.
+ if (AmtSum >= TypeBits)
+ AmtSum = TypeBits-1;
+
+ Value *Shift = Builder->CreateAShr(X, ConstantInt::get(Ty, AmtSum));
+
+ APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
+ return BinaryOperator::CreateAnd(Shift, ConstantInt::get(*Context, Mask));
+ }
+
+ // Okay, if we get here, one shift must be left, and the other shift must be
+ // right. See if the amounts are equal.
+ if (ShiftAmt1 == ShiftAmt2) {
+ // If we have ((X >>? C) << C), turn this into X & (-1 << C).
+ if (I.getOpcode() == Instruction::Shl) {
+ APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt1));
+ return BinaryOperator::CreateAnd(X, ConstantInt::get(*Context, Mask));
+ }
+ // If we have ((X << C) >>u C), turn this into X & (-1 >>u C).
+ if (I.getOpcode() == Instruction::LShr) {
+ APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt1));
+ return BinaryOperator::CreateAnd(X, ConstantInt::get(*Context, Mask));
+ }
+ // We can simplify ((X << C) >>s C) into a trunc + sext.
+ // NOTE: we could do this for any C, but that would make 'unusual' integer
+ // types. For now, just stick to ones well-supported by the code
+ // generators.
+ const Type *SExtType = 0;
+ switch (Ty->getBitWidth() - ShiftAmt1) {
+ case 1 :
+ case 8 :
+ case 16 :
+ case 32 :
+ case 64 :
+ case 128:
+ SExtType = IntegerType::get(*Context, Ty->getBitWidth() - ShiftAmt1);
+ break;
+ default: break;
+ }
+ if (SExtType)
+ return new SExtInst(Builder->CreateTrunc(X, SExtType, "sext"), Ty);
+ // Otherwise, we can't handle it yet.
+ } else if (ShiftAmt1 < ShiftAmt2) {
+ uint32_t ShiftDiff = ShiftAmt2-ShiftAmt1;
+
+ // (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)
+ if (I.getOpcode() == Instruction::Shl) {
+ assert(ShiftOp->getOpcode() == Instruction::LShr ||
+ ShiftOp->getOpcode() == Instruction::AShr);
+ Value *Shift = Builder->CreateShl(X, ConstantInt::get(Ty, ShiftDiff));
+
+ APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
+ return BinaryOperator::CreateAnd(Shift,
+ ConstantInt::get(*Context, Mask));
+ }
+
+ // (X << C1) >>u C2 --> X >>u (C2-C1) & (-1 >> C2)
+ if (I.getOpcode() == Instruction::LShr) {
+ assert(ShiftOp->getOpcode() == Instruction::Shl);
+ Value *Shift = Builder->CreateLShr(X, ConstantInt::get(Ty, ShiftDiff));
+
+ APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
+ return BinaryOperator::CreateAnd(Shift,
+ ConstantInt::get(*Context, Mask));
+ }
+
+ // We can't handle (X << C1) >>s C2, it shifts arbitrary bits in.
+ } else {
+ assert(ShiftAmt2 < ShiftAmt1);
+ uint32_t ShiftDiff = ShiftAmt1-ShiftAmt2;
+
+ // (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)
+ if (I.getOpcode() == Instruction::Shl) {
+ assert(ShiftOp->getOpcode() == Instruction::LShr ||
+ ShiftOp->getOpcode() == Instruction::AShr);
+ Value *Shift = Builder->CreateBinOp(ShiftOp->getOpcode(), X,
+ ConstantInt::get(Ty, ShiftDiff));
+
+ APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
+ return BinaryOperator::CreateAnd(Shift,
+ ConstantInt::get(*Context, Mask));
+ }
+
+ // (X << C1) >>u C2 --> X << (C1-C2) & (-1 >> C2)
+ if (I.getOpcode() == Instruction::LShr) {
+ assert(ShiftOp->getOpcode() == Instruction::Shl);
+ Value *Shift = Builder->CreateShl(X, ConstantInt::get(Ty, ShiftDiff));
+
+ APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
+ return BinaryOperator::CreateAnd(Shift,
+ ConstantInt::get(*Context, Mask));
+ }
+
+ // We can't handle (X << C1) >>a C2, it shifts arbitrary bits in.
+ }
+ }
+ return 0;
+}
+
+
+/// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
+/// expression. If so, decompose it, returning some value X, such that Val is
+/// X*Scale+Offset.
+///
+static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
+ int &Offset, LLVMContext *Context) {
+ assert(Val->getType() == Type::getInt32Ty(*Context) &&
+ "Unexpected allocation size type!");
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
+ Offset = CI->getZExtValue();
+ Scale = 0;
+ return ConstantInt::get(Type::getInt32Ty(*Context), 0);
+ } else if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ if (I->getOpcode() == Instruction::Shl) {
+ // This is a value scaled by '1 << the shift amt'.
+ Scale = 1U << RHS->getZExtValue();
+ Offset = 0;
+ return I->getOperand(0);
+ } else if (I->getOpcode() == Instruction::Mul) {
+ // This value is scaled by 'RHS'.
+ Scale = RHS->getZExtValue();
+ Offset = 0;
+ return I->getOperand(0);
+ } else if (I->getOpcode() == Instruction::Add) {
+ // We have X+C. Check to see if we really have (X*C2)+C1,
+ // where C1 is divisible by C2.
+ unsigned SubScale;
+ Value *SubVal =
+ DecomposeSimpleLinearExpr(I->getOperand(0), SubScale,
+ Offset, Context);
+ Offset += RHS->getZExtValue();
+ Scale = SubScale;
+ return SubVal;
+ }
+ }
+ }
+
+ // Otherwise, we can't look past this.
+ Scale = 1;
+ Offset = 0;
+ return Val;
+}
+
+
+/// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
+/// try to eliminate the cast by moving the type information into the alloc.
+Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
+ AllocaInst &AI) {
+ const PointerType *PTy = cast<PointerType>(CI.getType());
+
+ BuilderTy AllocaBuilder(*Builder);
+ AllocaBuilder.SetInsertPoint(AI.getParent(), &AI);
+
+ // Remove any uses of AI that are dead.
+ assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
+
+ for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
+ Instruction *User = cast<Instruction>(*UI++);
+ if (isInstructionTriviallyDead(User)) {
+ while (UI != E && *UI == User)
+ ++UI; // If this instruction uses AI more than once, don't break UI.
+
+ ++NumDeadInst;
+ DEBUG(errs() << "IC: DCE: " << *User << '\n');
+ EraseInstFromFunction(*User);
+ }
+ }
+
+ // This requires TargetData to get the alloca alignment and size information.
+ if (!TD) return 0;
+
+ // Get the type really allocated and the type casted to.
+ const Type *AllocElTy = AI.getAllocatedType();
+ const Type *CastElTy = PTy->getElementType();
+ if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
+
+ unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy);
+ unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy);
+ if (CastElTyAlign < AllocElTyAlign) return 0;
+
+ // If the allocation has multiple uses, only promote it if we are strictly
+ // increasing the alignment of the resultant allocation. If we keep it the
+ // same, we open the door to infinite loops of various kinds. (A reference
+ // from a dbg.declare doesn't count as a use for this purpose.)
+ if (!AI.hasOneUse() && !hasOneUsePlusDeclare(&AI) &&
+ CastElTyAlign == AllocElTyAlign) return 0;
+
+ uint64_t AllocElTySize = TD->getTypeAllocSize(AllocElTy);
+ uint64_t CastElTySize = TD->getTypeAllocSize(CastElTy);
+ if (CastElTySize == 0 || AllocElTySize == 0) return 0;
+
+ // See if we can satisfy the modulus by pulling a scale out of the array
+ // size argument.
+ unsigned ArraySizeScale;
+ int ArrayOffset;
+ Value *NumElements = // See if the array size is a decomposable linear expr.
+ DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale,
+ ArrayOffset, Context);
+
+ // If we can now satisfy the modulus, by using a non-1 scale, we really can
+ // do the xform.
+ if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
+ (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
+
+ unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
+ Value *Amt = 0;
+ if (Scale == 1) {
+ Amt = NumElements;
+ } else {
+ Amt = ConstantInt::get(Type::getInt32Ty(*Context), Scale);
+ // Insert before the alloca, not before the cast.
+ Amt = AllocaBuilder.CreateMul(Amt, NumElements, "tmp");
+ }
+
+ if (int Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
+ Value *Off = ConstantInt::get(Type::getInt32Ty(*Context), Offset, true);
+ Amt = AllocaBuilder.CreateAdd(Amt, Off, "tmp");
+ }
+
+ AllocaInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt);
+ New->setAlignment(AI.getAlignment());
+ New->takeName(&AI);
+
+ // If the allocation has one real use plus a dbg.declare, just remove the
+ // declare.
+ if (DbgDeclareInst *DI = hasOneUsePlusDeclare(&AI)) {
+ EraseInstFromFunction(*DI);
+ }
+ // If the allocation has multiple real uses, insert a cast and change all
+ // things that used it to use the new cast. This will also hack on CI, but it
+ // will die soon.
+ else if (!AI.hasOneUse()) {
+ // New is the allocation instruction, pointer typed. AI is the original
+ // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
+ Value *NewCast = AllocaBuilder.CreateBitCast(New, AI.getType(), "tmpcast");
+ AI.replaceAllUsesWith(NewCast);
+ }
+ return ReplaceInstUsesWith(CI, New);
+}
+
+/// CanEvaluateInDifferentType - Return true if we can take the specified value
+/// and return it as type Ty without inserting any new casts and without
+/// changing the computed value. This is used by code that tries to decide
+/// whether promoting or shrinking integer operations to wider or smaller types
+/// will allow us to eliminate a truncate or extend.
+///
+/// This is a truncation operation if Ty is smaller than V->getType(), or an
+/// extension operation if Ty is larger.
+///
+/// If CastOpc is a truncation, then Ty will be a type smaller than V. We
+/// should return true if trunc(V) can be computed by computing V in the smaller
+/// type. If V is an instruction, then trunc(inst(x,y)) can be computed as
+/// inst(trunc(x),trunc(y)), which only makes sense if x and y can be
+/// efficiently truncated.
+///
+/// If CastOpc is a sext or zext, we are asking if the low bits of the value can
+/// bit computed in a larger type, which is then and'd or sext_in_reg'd to get
+/// the final result.
+bool InstCombiner::CanEvaluateInDifferentType(Value *V, const Type *Ty,
+ unsigned CastOpc,
+ int &NumCastsRemoved){
+ // We can always evaluate constants in another type.
+ if (isa<Constant>(V))
+ return true;
+
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) return false;
+
+ const Type *OrigTy = V->getType();
+
+ // If this is an extension or truncate, we can often eliminate it.
+ if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) {
+ // If this is a cast from the destination type, we can trivially eliminate
+ // it, and this will remove a cast overall.
+ if (I->getOperand(0)->getType() == Ty) {
+ // If the first operand is itself a cast, and is eliminable, do not count
+ // this as an eliminable cast. We would prefer to eliminate those two
+ // casts first.
+ if (!isa<CastInst>(I->getOperand(0)) && I->hasOneUse())
+ ++NumCastsRemoved;
+ return true;
+ }
+ }
+
+ // We can't extend or shrink something that has multiple uses: doing so would
+ // require duplicating the instruction in general, which isn't profitable.
+ if (!I->hasOneUse()) return false;
+
+ unsigned Opc = I->getOpcode();
+ switch (Opc) {
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Mul:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ // These operators can all arbitrarily be extended or truncated.
+ return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
+ NumCastsRemoved) &&
+ CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
+ NumCastsRemoved);
+
+ case Instruction::UDiv:
+ case Instruction::URem: {
+ // UDiv and URem can be truncated if all the truncated bits are zero.
+ uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
+ uint32_t BitWidth = Ty->getScalarSizeInBits();
+ if (BitWidth < OrigBitWidth) {
+ APInt Mask = APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth);
+ if (MaskedValueIsZero(I->getOperand(0), Mask) &&
+ MaskedValueIsZero(I->getOperand(1), Mask)) {
+ return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
+ NumCastsRemoved) &&
+ CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
+ NumCastsRemoved);
+ }
+ }
+ break;
+ }
+ case Instruction::Shl:
+ // If we are truncating the result of this SHL, and if it's a shift of a
+ // constant amount, we can always perform a SHL in a smaller type.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ uint32_t BitWidth = Ty->getScalarSizeInBits();
+ if (BitWidth < OrigTy->getScalarSizeInBits() &&
+ CI->getLimitedValue(BitWidth) < BitWidth)
+ return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
+ NumCastsRemoved);
+ }
+ break;
+ case Instruction::LShr:
+ // If this is a truncate of a logical shr, we can truncate it to a smaller
+ // lshr iff we know that the bits we would otherwise be shifting in are
+ // already zeros.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
+ uint32_t BitWidth = Ty->getScalarSizeInBits();
+ if (BitWidth < OrigBitWidth &&
+ MaskedValueIsZero(I->getOperand(0),
+ APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
+ CI->getLimitedValue(BitWidth) < BitWidth) {
+ return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
+ NumCastsRemoved);
+ }
+ }
+ break;
+ case Instruction::ZExt:
+ case Instruction::SExt:
+ case Instruction::Trunc:
+ // If this is the same kind of case as our original (e.g. zext+zext), we
+ // can safely replace it. Note that replacing it does not reduce the number
+ // of casts in the input.
+ if (Opc == CastOpc)
+ return true;
+
+ // sext (zext ty1), ty2 -> zext ty2
+ if (CastOpc == Instruction::SExt && Opc == Instruction::ZExt)
+ return true;
+ break;
+ case Instruction::Select: {
+ SelectInst *SI = cast<SelectInst>(I);
+ return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc,
+ NumCastsRemoved) &&
+ CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc,
+ NumCastsRemoved);
+ }
+ case Instruction::PHI: {
+ // We can change a phi if we can change all operands.
+ PHINode *PN = cast<PHINode>(I);
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ if (!CanEvaluateInDifferentType(PN->getIncomingValue(i), Ty, CastOpc,
+ NumCastsRemoved))
+ return false;
+ return true;
+ }
+ default:
+ // TODO: Can handle more cases here.
+ break;
+ }
+
+ return false;
+}
+
+/// EvaluateInDifferentType - Given an expression that
+/// CanEvaluateInDifferentType returns true for, actually insert the code to
+/// evaluate the expression.
+Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
+ bool isSigned) {
+ if (Constant *C = dyn_cast<Constant>(V))
+ return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
+
+ // Otherwise, it must be an instruction.
+ Instruction *I = cast<Instruction>(V);
+ Instruction *Res = 0;
+ unsigned Opc = I->getOpcode();
+ switch (Opc) {
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Mul:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ case Instruction::AShr:
+ case Instruction::LShr:
+ case Instruction::Shl:
+ case Instruction::UDiv:
+ case Instruction::URem: {
+ Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
+ Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
+ Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
+ break;
+ }
+ case Instruction::Trunc:
+ case Instruction::ZExt:
+ case Instruction::SExt:
+ // If the source type of the cast is the type we're trying for then we can
+ // just return the source. There's no need to insert it because it is not
+ // new.
+ if (I->getOperand(0)->getType() == Ty)
+ return I->getOperand(0);
+
+ // Otherwise, must be the same type of cast, so just reinsert a new one.
+ Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),Ty);
+ break;
+ case Instruction::Select: {
+ Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
+ Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
+ Res = SelectInst::Create(I->getOperand(0), True, False);
+ break;
+ }
+ case Instruction::PHI: {
+ PHINode *OPN = cast<PHINode>(I);
+ PHINode *NPN = PHINode::Create(Ty);
+ for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
+ Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
+ NPN->addIncoming(V, OPN->getIncomingBlock(i));
+ }
+ Res = NPN;
+ break;
+ }
+ default:
+ // TODO: Can handle more cases here.
+ llvm_unreachable("Unreachable!");
+ break;
+ }
+
+ Res->takeName(I);
+ return InsertNewInstBefore(Res, *I);
+}
+
+/// @brief Implement the transforms common to all CastInst visitors.
+Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
+ Value *Src = CI.getOperand(0);
+
+ // Many cases of "cast of a cast" are eliminable. If it's eliminable we just
+ // eliminate it now.
+ if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
+ if (Instruction::CastOps opc =
+ isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) {
+ // The first cast (CSrc) is eliminable so we need to fix up or replace
+ // the second cast (CI). CSrc will then have a good chance of being dead.
+ return CastInst::Create(opc, CSrc->getOperand(0), CI.getType());
+ }
+ }
+
+ // If we are casting a select then fold the cast into the select
+ if (SelectInst *SI = dyn_cast<SelectInst>(Src))
+ if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
+ return NV;
+
+ // If we are casting a PHI then fold the cast into the PHI
+ if (isa<PHINode>(Src)) {
+ // We don't do this if this would create a PHI node with an illegal type if
+ // it is currently legal.
+ if (!isa<IntegerType>(Src->getType()) ||
+ !isa<IntegerType>(CI.getType()) ||
+ ShouldChangeType(CI.getType(), Src->getType(), TD))
+ if (Instruction *NV = FoldOpIntoPhi(CI))
+ return NV;
+ }
+
+ return 0;
+}
+
+/// FindElementAtOffset - Given a type and a constant offset, determine whether
+/// or not there is a sequence of GEP indices into the type that will land us at
+/// the specified offset. If so, fill them into NewIndices and return the
+/// resultant element type, otherwise return null.
+static const Type *FindElementAtOffset(const Type *Ty, int64_t Offset,
+ SmallVectorImpl<Value*> &NewIndices,
+ const TargetData *TD,
+ LLVMContext *Context) {
+ if (!TD) return 0;
+ if (!Ty->isSized()) return 0;
+
+ // Start with the index over the outer type. Note that the type size
+ // might be zero (even if the offset isn't zero) if the indexed type
+ // is something like [0 x {int, int}]
+ const Type *IntPtrTy = TD->getIntPtrType(*Context);
+ int64_t FirstIdx = 0;
+ if (int64_t TySize = TD->getTypeAllocSize(Ty)) {
+ FirstIdx = Offset/TySize;
+ Offset -= FirstIdx*TySize;
+
+ // Handle hosts where % returns negative instead of values [0..TySize).
+ if (Offset < 0) {
+ --FirstIdx;
+ Offset += TySize;
+ assert(Offset >= 0);
+ }
+ assert((uint64_t)Offset < (uint64_t)TySize && "Out of range offset");
+ }
+
+ NewIndices.push_back(ConstantInt::get(IntPtrTy, FirstIdx));
+
+ // Index into the types. If we fail, set OrigBase to null.
+ while (Offset) {
+ // Indexing into tail padding between struct/array elements.
+ if (uint64_t(Offset*8) >= TD->getTypeSizeInBits(Ty))
+ return 0;
+
+ if (const StructType *STy = dyn_cast<StructType>(Ty)) {
+ const StructLayout *SL = TD->getStructLayout(STy);
+ assert(Offset < (int64_t)SL->getSizeInBytes() &&
+ "Offset must stay within the indexed type");
+
+ unsigned Elt = SL->getElementContainingOffset(Offset);
+ NewIndices.push_back(ConstantInt::get(Type::getInt32Ty(*Context), Elt));
+
+ Offset -= SL->getElementOffset(Elt);
+ Ty = STy->getElementType(Elt);
+ } else if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
+ uint64_t EltSize = TD->getTypeAllocSize(AT->getElementType());
+ assert(EltSize && "Cannot index into a zero-sized array");
+ NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize));
+ Offset %= EltSize;
+ Ty = AT->getElementType();
+ } else {
+ // Otherwise, we can't index into the middle of this atomic type, bail.
+ return 0;
+ }
+ }
+
+ return Ty;
+}
+
+/// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint)
+Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
+ Value *Src = CI.getOperand(0);
+
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
+ // If casting the result of a getelementptr instruction with no offset, turn
+ // this into a cast of the original pointer!
+ if (GEP->hasAllZeroIndices()) {
+ // Changing the cast operand is usually not a good idea but it is safe
+ // here because the pointer operand is being replaced with another
+ // pointer operand so the opcode doesn't need to change.
+ Worklist.Add(GEP);
+ CI.setOperand(0, GEP->getOperand(0));
+ return &CI;
+ }
+
+ // If the GEP has a single use, and the base pointer is a bitcast, and the
+ // GEP computes a constant offset, see if we can convert these three
+ // instructions into fewer. This typically happens with unions and other
+ // non-type-safe code.
+ if (TD && GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0))) {
+ if (GEP->hasAllConstantIndices()) {
+ // We are guaranteed to get a constant from EmitGEPOffset.
+ ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP, *this));
+ int64_t Offset = OffsetV->getSExtValue();
+
+ // Get the base pointer input of the bitcast, and the type it points to.
+ Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0);
+ const Type *GEPIdxTy =
+ cast<PointerType>(OrigBase->getType())->getElementType();
+ SmallVector<Value*, 8> NewIndices;
+ if (FindElementAtOffset(GEPIdxTy, Offset, NewIndices, TD, Context)) {
+ // If we were able to index down into an element, create the GEP
+ // and bitcast the result. This eliminates one bitcast, potentially
+ // two.
+ Value *NGEP = cast<GEPOperator>(GEP)->isInBounds() ?
+ Builder->CreateInBoundsGEP(OrigBase,
+ NewIndices.begin(), NewIndices.end()) :
+ Builder->CreateGEP(OrigBase, NewIndices.begin(), NewIndices.end());
+ NGEP->takeName(GEP);
+
+ if (isa<BitCastInst>(CI))
+ return new BitCastInst(NGEP, CI.getType());
+ assert(isa<PtrToIntInst>(CI));
+ return new PtrToIntInst(NGEP, CI.getType());
+ }
+ }
+ }
+ }
+
+ return commonCastTransforms(CI);
+}
+
+/// commonIntCastTransforms - This function implements the common transforms
+/// for trunc, zext, and sext.
+Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
+ if (Instruction *Result = commonCastTransforms(CI))
+ return Result;
+
+ Value *Src = CI.getOperand(0);
+ const Type *SrcTy = Src->getType();
+ const Type *DestTy = CI.getType();
+ uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
+ uint32_t DestBitSize = DestTy->getScalarSizeInBits();
+
+ // See if we can simplify any instructions used by the LHS whose sole
+ // purpose is to compute bits we don't care about.
+ if (SimplifyDemandedInstructionBits(CI))
+ return &CI;
+
+ // If the source isn't an instruction or has more than one use then we
+ // can't do anything more.
+ Instruction *SrcI = dyn_cast<Instruction>(Src);
+ if (!SrcI || !Src->hasOneUse())
+ return 0;
+
+ // Attempt to propagate the cast into the instruction for int->int casts.
+ int NumCastsRemoved = 0;
+ // Only do this if the dest type is a simple type, don't convert the
+ // expression tree to something weird like i93 unless the source is also
+ // strange.
+ if ((isa<VectorType>(DestTy) ||
+ ShouldChangeType(SrcI->getType(), DestTy, TD)) &&
+ CanEvaluateInDifferentType(SrcI, DestTy,
+ CI.getOpcode(), NumCastsRemoved)) {
+ // If this cast is a truncate, evaluting in a different type always
+ // eliminates the cast, so it is always a win. If this is a zero-extension,
+ // we need to do an AND to maintain the clear top-part of the computation,
+ // so we require that the input have eliminated at least one cast. If this
+ // is a sign extension, we insert two new casts (to do the extension) so we
+ // require that two casts have been eliminated.
+ bool DoXForm = false;
+ bool JustReplace = false;
+ switch (CI.getOpcode()) {
+ default:
+ // All the others use floating point so we shouldn't actually
+ // get here because of the check above.
+ llvm_unreachable("Unknown cast type");
+ case Instruction::Trunc:
+ DoXForm = true;
+ break;
+ case Instruction::ZExt: {
+ DoXForm = NumCastsRemoved >= 1;
+
+ if (!DoXForm && 0) {
+ // If it's unnecessary to issue an AND to clear the high bits, it's
+ // always profitable to do this xform.
+ Value *TryRes = EvaluateInDifferentType(SrcI, DestTy, false);
+ APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
+ if (MaskedValueIsZero(TryRes, Mask))
+ return ReplaceInstUsesWith(CI, TryRes);
+
+ if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
+ if (TryI->use_empty())
+ EraseInstFromFunction(*TryI);
+ }
+ break;
+ }
+ case Instruction::SExt: {
+ DoXForm = NumCastsRemoved >= 2;
+ if (!DoXForm && !isa<TruncInst>(SrcI) && 0) {
+ // If we do not have to emit the truncate + sext pair, then it's always
+ // profitable to do this xform.
+ //
+ // It's not safe to eliminate the trunc + sext pair if one of the
+ // eliminated cast is a truncate. e.g.
+ // t2 = trunc i32 t1 to i16
+ // t3 = sext i16 t2 to i32
+ // !=
+ // i32 t1
+ Value *TryRes = EvaluateInDifferentType(SrcI, DestTy, true);
+ unsigned NumSignBits = ComputeNumSignBits(TryRes);
+ if (NumSignBits > (DestBitSize - SrcBitSize))
+ return ReplaceInstUsesWith(CI, TryRes);
+
+ if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
+ if (TryI->use_empty())
+ EraseInstFromFunction(*TryI);
+ }
+ break;
+ }
+ }
+
+ if (DoXForm) {
+ DEBUG(errs() << "ICE: EvaluateInDifferentType converting expression type"
+ " to avoid cast: " << CI);
+ Value *Res = EvaluateInDifferentType(SrcI, DestTy,
+ CI.getOpcode() == Instruction::SExt);
+ if (JustReplace)
+ // Just replace this cast with the result.
+ return ReplaceInstUsesWith(CI, Res);
+
+ assert(Res->getType() == DestTy);
+ switch (CI.getOpcode()) {
+ default: llvm_unreachable("Unknown cast type!");
+ case Instruction::Trunc:
+ // Just replace this cast with the result.
+ return ReplaceInstUsesWith(CI, Res);
+ case Instruction::ZExt: {
+ assert(SrcBitSize < DestBitSize && "Not a zext?");
+
+ // If the high bits are already zero, just replace this cast with the
+ // result.
+ APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
+ if (MaskedValueIsZero(Res, Mask))
+ return ReplaceInstUsesWith(CI, Res);
+
+ // We need to emit an AND to clear the high bits.
+ Constant *C = ConstantInt::get(*Context,
+ APInt::getLowBitsSet(DestBitSize, SrcBitSize));
+ return BinaryOperator::CreateAnd(Res, C);
+ }
+ case Instruction::SExt: {
+ // If the high bits are already filled with sign bit, just replace this
+ // cast with the result.
+ unsigned NumSignBits = ComputeNumSignBits(Res);
+ if (NumSignBits > (DestBitSize - SrcBitSize))
+ return ReplaceInstUsesWith(CI, Res);
+
+ // We need to emit a cast to truncate, then a cast to sext.
+ return new SExtInst(Builder->CreateTrunc(Res, Src->getType()), DestTy);
+ }
+ }
+ }
+ }
+
+ Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
+ Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
+
+ switch (SrcI->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Mul:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ // If we are discarding information, rewrite.
+ if (DestBitSize < SrcBitSize && DestBitSize != 1) {
+ // Don't insert two casts unless at least one can be eliminated.
+ if (!ValueRequiresCast(CI.getOpcode(), Op1, DestTy, TD) ||
+ !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
+ Value *Op0c = Builder->CreateTrunc(Op0, DestTy, Op0->getName());
+ Value *Op1c = Builder->CreateTrunc(Op1, DestTy, Op1->getName());
+ return BinaryOperator::Create(
+ cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
+ }
+ }
+
+ // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
+ if (isa<ZExtInst>(CI) && SrcBitSize == 1 &&
+ SrcI->getOpcode() == Instruction::Xor &&
+ Op1 == ConstantInt::getTrue(*Context) &&
+ (!Op0->hasOneUse() || !isa<CmpInst>(Op0))) {
+ Value *New = Builder->CreateZExt(Op0, DestTy, Op0->getName());
+ return BinaryOperator::CreateXor(New,
+ ConstantInt::get(CI.getType(), 1));
+ }
+ break;
+
+ case Instruction::Shl: {
+ // Canonicalize trunc inside shl, if we can.
+ ConstantInt *CI = dyn_cast<ConstantInt>(Op1);
+ if (CI && DestBitSize < SrcBitSize &&
+ CI->getLimitedValue(DestBitSize) < DestBitSize) {
+ Value *Op0c = Builder->CreateTrunc(Op0, DestTy, Op0->getName());
+ Value *Op1c = Builder->CreateTrunc(Op1, DestTy, Op1->getName());
+ return BinaryOperator::CreateShl(Op0c, Op1c);
+ }
+ break;
+ }
+ }
+ return 0;
+}
+
+Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
+ if (Instruction *Result = commonIntCastTransforms(CI))
+ return Result;
+
+ Value *Src = CI.getOperand(0);
+ const Type *Ty = CI.getType();
+ uint32_t DestBitWidth = Ty->getScalarSizeInBits();
+ uint32_t SrcBitWidth = Src->getType()->getScalarSizeInBits();
+
+ // Canonicalize trunc x to i1 -> (icmp ne (and x, 1), 0)
+ if (DestBitWidth == 1) {
+ Constant *One = ConstantInt::get(Src->getType(), 1);
+ Src = Builder->CreateAnd(Src, One, "tmp");
+ Value *Zero = Constant::getNullValue(Src->getType());
+ return new ICmpInst(ICmpInst::ICMP_NE, Src, Zero);
+ }
+
+ // Optimize trunc(lshr(), c) to pull the shift through the truncate.
+ ConstantInt *ShAmtV = 0;
+ Value *ShiftOp = 0;
+ if (Src->hasOneUse() &&
+ match(Src, m_LShr(m_Value(ShiftOp), m_ConstantInt(ShAmtV)))) {
+ uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth);
+
+ // Get a mask for the bits shifting in.
+ APInt Mask(APInt::getLowBitsSet(SrcBitWidth, ShAmt).shl(DestBitWidth));
+ if (MaskedValueIsZero(ShiftOp, Mask)) {
+ if (ShAmt >= DestBitWidth) // All zeros.
+ return ReplaceInstUsesWith(CI, Constant::getNullValue(Ty));
+
+ // Okay, we can shrink this. Truncate the input, then return a new
+ // shift.
+ Value *V1 = Builder->CreateTrunc(ShiftOp, Ty, ShiftOp->getName());
+ Value *V2 = ConstantExpr::getTrunc(ShAmtV, Ty);
+ return BinaryOperator::CreateLShr(V1, V2);
+ }
+ }
+
+ return 0;
+}
+
+/// transformZExtICmp - Transform (zext icmp) to bitwise / integer operations
+/// in order to eliminate the icmp.
+Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI,
+ bool DoXform) {
+ // If we are just checking for a icmp eq of a single bit and zext'ing it
+ // to an integer, then shift the bit to the appropriate place and then
+ // cast to integer to avoid the comparison.
+ if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
+ const APInt &Op1CV = Op1C->getValue();
+
+ // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
+ // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
+ if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
+ (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) {
+ if (!DoXform) return ICI;
+
+ Value *In = ICI->getOperand(0);
+ Value *Sh = ConstantInt::get(In->getType(),
+ In->getType()->getScalarSizeInBits()-1);
+ In = Builder->CreateLShr(In, Sh, In->getName()+".lobit");
+ if (In->getType() != CI.getType())
+ In = Builder->CreateIntCast(In, CI.getType(), false/*ZExt*/, "tmp");
+
+ if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
+ Constant *One = ConstantInt::get(In->getType(), 1);
+ In = Builder->CreateXor(In, One, In->getName()+".not");
+ }
+
+ return ReplaceInstUsesWith(CI, In);
+ }
+
+
+
+ // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
+ // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
+ // zext (X == 1) to i32 --> X iff X has only the low bit set.
+ // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
+ // zext (X != 0) to i32 --> X iff X has only the low bit set.
+ // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
+ // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
+ // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
+ if ((Op1CV == 0 || Op1CV.isPowerOf2()) &&
+ // This only works for EQ and NE
+ ICI->isEquality()) {
+ // If Op1C some other power of two, convert:
+ uint32_t BitWidth = Op1C->getType()->getBitWidth();
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ APInt TypeMask(APInt::getAllOnesValue(BitWidth));
+ ComputeMaskedBits(ICI->getOperand(0), TypeMask, KnownZero, KnownOne);
+
+ APInt KnownZeroMask(~KnownZero);
+ if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
+ if (!DoXform) return ICI;
+
+ bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
+ if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
+ // (X&4) == 2 --> false
+ // (X&4) != 2 --> true
+ Constant *Res = ConstantInt::get(Type::getInt1Ty(*Context), isNE);
+ Res = ConstantExpr::getZExt(Res, CI.getType());
+ return ReplaceInstUsesWith(CI, Res);
+ }
+
+ uint32_t ShiftAmt = KnownZeroMask.logBase2();
+ Value *In = ICI->getOperand(0);
+ if (ShiftAmt) {
+ // Perform a logical shr by shiftamt.
+ // Insert the shift to put the result in the low bit.
+ In = Builder->CreateLShr(In, ConstantInt::get(In->getType(),ShiftAmt),
+ In->getName()+".lobit");
+ }
+
+ if ((Op1CV != 0) == isNE) { // Toggle the low bit.
+ Constant *One = ConstantInt::get(In->getType(), 1);
+ In = Builder->CreateXor(In, One, "tmp");
+ }
+
+ if (CI.getType() == In->getType())
+ return ReplaceInstUsesWith(CI, In);
+ else
+ return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/);
+ }
+ }
+ }
+
+ // icmp ne A, B is equal to xor A, B when A and B only really have one bit.
+ // It is also profitable to transform icmp eq into not(xor(A, B)) because that
+ // may lead to additional simplifications.
+ if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) {
+ if (const IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) {
+ uint32_t BitWidth = ITy->getBitWidth();
+ Value *LHS = ICI->getOperand(0);
+ Value *RHS = ICI->getOperand(1);
+
+ APInt KnownZeroLHS(BitWidth, 0), KnownOneLHS(BitWidth, 0);
+ APInt KnownZeroRHS(BitWidth, 0), KnownOneRHS(BitWidth, 0);
+ APInt TypeMask(APInt::getAllOnesValue(BitWidth));
+ ComputeMaskedBits(LHS, TypeMask, KnownZeroLHS, KnownOneLHS);
+ ComputeMaskedBits(RHS, TypeMask, KnownZeroRHS, KnownOneRHS);
+
+ if (KnownZeroLHS == KnownZeroRHS && KnownOneLHS == KnownOneRHS) {
+ APInt KnownBits = KnownZeroLHS | KnownOneLHS;
+ APInt UnknownBit = ~KnownBits;
+ if (UnknownBit.countPopulation() == 1) {
+ if (!DoXform) return ICI;
+
+ Value *Result = Builder->CreateXor(LHS, RHS);
+
+ // Mask off any bits that are set and won't be shifted away.
+ if (KnownOneLHS.uge(UnknownBit))
+ Result = Builder->CreateAnd(Result,
+ ConstantInt::get(ITy, UnknownBit));
+
+ // Shift the bit we're testing down to the lsb.
+ Result = Builder->CreateLShr(
+ Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros()));
+
+ if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
+ Result = Builder->CreateXor(Result, ConstantInt::get(ITy, 1));
+ Result->takeName(ICI);
+ return ReplaceInstUsesWith(CI, Result);
+ }
+ }
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
+ // If one of the common conversion will work, do it.
+ if (Instruction *Result = commonIntCastTransforms(CI))
+ return Result;
+
+ Value *Src = CI.getOperand(0);
+
+ // If this is a TRUNC followed by a ZEXT then we are dealing with integral
+ // types and if the sizes are just right we can convert this into a logical
+ // 'and' which will be much cheaper than the pair of casts.
+ if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast
+ // Get the sizes of the types involved. We know that the intermediate type
+ // will be smaller than A or C, but don't know the relation between A and C.
+ Value *A = CSrc->getOperand(0);
+ unsigned SrcSize = A->getType()->getScalarSizeInBits();
+ unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
+ unsigned DstSize = CI.getType()->getScalarSizeInBits();
+ // If we're actually extending zero bits, then if
+ // SrcSize < DstSize: zext(a & mask)
+ // SrcSize == DstSize: a & mask
+ // SrcSize > DstSize: trunc(a) & mask
+ if (SrcSize < DstSize) {
+ APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
+ Constant *AndConst = ConstantInt::get(A->getType(), AndValue);
+ Value *And = Builder->CreateAnd(A, AndConst, CSrc->getName()+".mask");
+ return new ZExtInst(And, CI.getType());
+ }
+
+ if (SrcSize == DstSize) {
+ APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
+ return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(),
+ AndValue));
+ }
+ if (SrcSize > DstSize) {
+ Value *Trunc = Builder->CreateTrunc(A, CI.getType(), "tmp");
+ APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
+ return BinaryOperator::CreateAnd(Trunc,
+ ConstantInt::get(Trunc->getType(),
+ AndValue));
+ }
+ }
+
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
+ return transformZExtICmp(ICI, CI);
+
+ BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
+ if (SrcI && SrcI->getOpcode() == Instruction::Or) {
+ // zext (or icmp, icmp) --> or (zext icmp), (zext icmp) if at least one
+ // of the (zext icmp) will be transformed.
+ ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
+ ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
+ if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
+ (transformZExtICmp(LHS, CI, false) ||
+ transformZExtICmp(RHS, CI, false))) {
+ Value *LCast = Builder->CreateZExt(LHS, CI.getType(), LHS->getName());
+ Value *RCast = Builder->CreateZExt(RHS, CI.getType(), RHS->getName());
+ return BinaryOperator::Create(Instruction::Or, LCast, RCast);
+ }
+ }
+
+ // zext(trunc(t) & C) -> (t & zext(C)).
+ if (SrcI && SrcI->getOpcode() == Instruction::And && SrcI->hasOneUse())
+ if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
+ if (TruncInst *TI = dyn_cast<TruncInst>(SrcI->getOperand(0))) {
+ Value *TI0 = TI->getOperand(0);
+ if (TI0->getType() == CI.getType())
+ return
+ BinaryOperator::CreateAnd(TI0,
+ ConstantExpr::getZExt(C, CI.getType()));
+ }
+
+ // zext((trunc(t) & C) ^ C) -> ((t & zext(C)) ^ zext(C)).
+ if (SrcI && SrcI->getOpcode() == Instruction::Xor && SrcI->hasOneUse())
+ if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
+ if (BinaryOperator *And = dyn_cast<BinaryOperator>(SrcI->getOperand(0)))
+ if (And->getOpcode() == Instruction::And && And->hasOneUse() &&
+ And->getOperand(1) == C)
+ if (TruncInst *TI = dyn_cast<TruncInst>(And->getOperand(0))) {
+ Value *TI0 = TI->getOperand(0);
+ if (TI0->getType() == CI.getType()) {
+ Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
+ Value *NewAnd = Builder->CreateAnd(TI0, ZC, "tmp");
+ return BinaryOperator::CreateXor(NewAnd, ZC);
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitSExt(SExtInst &CI) {
+ if (Instruction *I = commonIntCastTransforms(CI))
+ return I;
+
+ Value *Src = CI.getOperand(0);
+
+ // Canonicalize sign-extend from i1 to a select.
+ if (Src->getType() == Type::getInt1Ty(*Context))
+ return SelectInst::Create(Src,
+ Constant::getAllOnesValue(CI.getType()),
+ Constant::getNullValue(CI.getType()));
+
+ // See if the value being truncated is already sign extended. If so, just
+ // eliminate the trunc/sext pair.
+ if (Operator::getOpcode(Src) == Instruction::Trunc) {
+ Value *Op = cast<User>(Src)->getOperand(0);
+ unsigned OpBits = Op->getType()->getScalarSizeInBits();
+ unsigned MidBits = Src->getType()->getScalarSizeInBits();
+ unsigned DestBits = CI.getType()->getScalarSizeInBits();
+ unsigned NumSignBits = ComputeNumSignBits(Op);
+
+ if (OpBits == DestBits) {
+ // Op is i32, Mid is i8, and Dest is i32. If Op has more than 24 sign
+ // bits, it is already ready.
+ if (NumSignBits > DestBits-MidBits)
+ return ReplaceInstUsesWith(CI, Op);
+ } else if (OpBits < DestBits) {
+ // Op is i32, Mid is i8, and Dest is i64. If Op has more than 24 sign
+ // bits, just sext from i32.
+ if (NumSignBits > OpBits-MidBits)
+ return new SExtInst(Op, CI.getType(), "tmp");
+ } else {
+ // Op is i64, Mid is i8, and Dest is i32. If Op has more than 56 sign
+ // bits, just truncate to i32.
+ if (NumSignBits > OpBits-MidBits)
+ return new TruncInst(Op, CI.getType(), "tmp");
+ }
+ }
+
+ // If the input is a shl/ashr pair of a same constant, then this is a sign
+ // extension from a smaller value. If we could trust arbitrary bitwidth
+ // integers, we could turn this into a truncate to the smaller bit and then
+ // use a sext for the whole extension. Since we don't, look deeper and check
+ // for a truncate. If the source and dest are the same type, eliminate the
+ // trunc and extend and just do shifts. For example, turn:
+ // %a = trunc i32 %i to i8
+ // %b = shl i8 %a, 6
+ // %c = ashr i8 %b, 6
+ // %d = sext i8 %c to i32
+ // into:
+ // %a = shl i32 %i, 30
+ // %d = ashr i32 %a, 30
+ Value *A = 0;
+ ConstantInt *BA = 0, *CA = 0;
+ if (match(Src, m_AShr(m_Shl(m_Value(A), m_ConstantInt(BA)),
+ m_ConstantInt(CA))) &&
+ BA == CA && isa<TruncInst>(A)) {
+ Value *I = cast<TruncInst>(A)->getOperand(0);
+ if (I->getType() == CI.getType()) {
+ unsigned MidSize = Src->getType()->getScalarSizeInBits();
+ unsigned SrcDstSize = CI.getType()->getScalarSizeInBits();
+ unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
+ Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
+ I = Builder->CreateShl(I, ShAmtV, CI.getName());
+ return BinaryOperator::CreateAShr(I, ShAmtV);
+ }
+ }
+
+ return 0;
+}
+
+/// FitsInFPType - Return a Constant* for the specified FP constant if it fits
+/// in the specified FP type without changing its value.
+static Constant *FitsInFPType(ConstantFP *CFP, const fltSemantics &Sem,
+ LLVMContext *Context) {
+ bool losesInfo;
+ APFloat F = CFP->getValueAPF();
+ (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
+ if (!losesInfo)
+ return ConstantFP::get(*Context, F);
+ return 0;
+}
+
+/// LookThroughFPExtensions - If this is an fp extension instruction, look
+/// through it until we get the source value.
+static Value *LookThroughFPExtensions(Value *V, LLVMContext *Context) {
+ if (Instruction *I = dyn_cast<Instruction>(V))
+ if (I->getOpcode() == Instruction::FPExt)
+ return LookThroughFPExtensions(I->getOperand(0), Context);
+
+ // If this value is a constant, return the constant in the smallest FP type
+ // that can accurately represent it. This allows us to turn
+ // (float)((double)X+2.0) into x+2.0f.
+ if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
+ if (CFP->getType() == Type::getPPC_FP128Ty(*Context))
+ return V; // No constant folding of this.
+ // See if the value can be truncated to float and then reextended.
+ if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle, Context))
+ return V;
+ if (CFP->getType() == Type::getDoubleTy(*Context))
+ return V; // Won't shrink.
+ if (Value *V = FitsInFPType(CFP, APFloat::IEEEdouble, Context))
+ return V;
+ // Don't try to shrink to various long double types.
+ }
+
+ return V;
+}
+
+Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) {
+ if (Instruction *I = commonCastTransforms(CI))
+ return I;
+
+ // If we have fptrunc(fadd (fpextend x), (fpextend y)), where x and y are
+ // smaller than the destination type, we can eliminate the truncate by doing
+ // the add as the smaller type. This applies to fadd/fsub/fmul/fdiv as well as
+ // many builtins (sqrt, etc).
+ BinaryOperator *OpI = dyn_cast<BinaryOperator>(CI.getOperand(0));
+ if (OpI && OpI->hasOneUse()) {
+ switch (OpI->getOpcode()) {
+ default: break;
+ case Instruction::FAdd:
+ case Instruction::FSub:
+ case Instruction::FMul:
+ case Instruction::FDiv:
+ case Instruction::FRem:
+ const Type *SrcTy = OpI->getType();
+ Value *LHSTrunc = LookThroughFPExtensions(OpI->getOperand(0), Context);
+ Value *RHSTrunc = LookThroughFPExtensions(OpI->getOperand(1), Context);
+ if (LHSTrunc->getType() != SrcTy &&
+ RHSTrunc->getType() != SrcTy) {
+ unsigned DstSize = CI.getType()->getScalarSizeInBits();
+ // If the source types were both smaller than the destination type of
+ // the cast, do this xform.
+ if (LHSTrunc->getType()->getScalarSizeInBits() <= DstSize &&
+ RHSTrunc->getType()->getScalarSizeInBits() <= DstSize) {
+ LHSTrunc = Builder->CreateFPExt(LHSTrunc, CI.getType());
+ RHSTrunc = Builder->CreateFPExt(RHSTrunc, CI.getType());
+ return BinaryOperator::Create(OpI->getOpcode(), LHSTrunc, RHSTrunc);
+ }
+ }
+ break;
+ }
+ }
+ return 0;
+}
+
+Instruction *InstCombiner::visitFPExt(CastInst &CI) {
+ return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
+ Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
+ if (OpI == 0)
+ return commonCastTransforms(FI);
+
+ // fptoui(uitofp(X)) --> X
+ // fptoui(sitofp(X)) --> X
+ // This is safe if the intermediate type has enough bits in its mantissa to
+ // accurately represent all values of X. For example, do not do this with
+ // i64->float->i64. This is also safe for sitofp case, because any negative
+ // 'X' value would cause an undefined result for the fptoui.
+ if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
+ OpI->getOperand(0)->getType() == FI.getType() &&
+ (int)FI.getType()->getScalarSizeInBits() < /*extra bit for sign */
+ OpI->getType()->getFPMantissaWidth())
+ return ReplaceInstUsesWith(FI, OpI->getOperand(0));
+
+ return commonCastTransforms(FI);
+}
+
+Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
+ Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
+ if (OpI == 0)
+ return commonCastTransforms(FI);
+
+ // fptosi(sitofp(X)) --> X
+ // fptosi(uitofp(X)) --> X
+ // This is safe if the intermediate type has enough bits in its mantissa to
+ // accurately represent all values of X. For example, do not do this with
+ // i64->float->i64. This is also safe for sitofp case, because any negative
+ // 'X' value would cause an undefined result for the fptoui.
+ if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
+ OpI->getOperand(0)->getType() == FI.getType() &&
+ (int)FI.getType()->getScalarSizeInBits() <=
+ OpI->getType()->getFPMantissaWidth())
+ return ReplaceInstUsesWith(FI, OpI->getOperand(0));
+
+ return commonCastTransforms(FI);
+}
+
+Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
+ return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
+ return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitPtrToInt(PtrToIntInst &CI) {
+ // If the destination integer type is smaller than the intptr_t type for
+ // this target, do a ptrtoint to intptr_t then do a trunc. This allows the
+ // trunc to be exposed to other transforms. Don't do this for extending
+ // ptrtoint's, because we don't know if the target sign or zero extends its
+ // pointers.
+ if (TD &&
+ CI.getType()->getScalarSizeInBits() < TD->getPointerSizeInBits()) {
+ Value *P = Builder->CreatePtrToInt(CI.getOperand(0),
+ TD->getIntPtrType(CI.getContext()),
+ "tmp");
+ return new TruncInst(P, CI.getType());
+ }
+
+ return commonPointerCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) {
+ // If the source integer type is larger than the intptr_t type for
+ // this target, do a trunc to the intptr_t type, then inttoptr of it. This
+ // allows the trunc to be exposed to other transforms. Don't do this for
+ // extending inttoptr's, because we don't know if the target sign or zero
+ // extends to pointers.
+ if (TD && CI.getOperand(0)->getType()->getScalarSizeInBits() >
+ TD->getPointerSizeInBits()) {
+ Value *P = Builder->CreateTrunc(CI.getOperand(0),
+ TD->getIntPtrType(CI.getContext()), "tmp");
+ return new IntToPtrInst(P, CI.getType());
+ }
+
+ if (Instruction *I = commonCastTransforms(CI))
+ return I;
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
+ // If the operands are integer typed then apply the integer transforms,
+ // otherwise just apply the common ones.
+ Value *Src = CI.getOperand(0);
+ const Type *SrcTy = Src->getType();
+ const Type *DestTy = CI.getType();
+
+ if (isa<PointerType>(SrcTy)) {
+ if (Instruction *I = commonPointerCastTransforms(CI))
+ return I;
+ } else {
+ if (Instruction *Result = commonCastTransforms(CI))
+ return Result;
+ }
+
+
+ // Get rid of casts from one type to the same type. These are useless and can
+ // be replaced by the operand.
+ if (DestTy == Src->getType())
+ return ReplaceInstUsesWith(CI, Src);
+
+ if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
+ const PointerType *SrcPTy = cast<PointerType>(SrcTy);
+ const Type *DstElTy = DstPTy->getElementType();
+ const Type *SrcElTy = SrcPTy->getElementType();
+
+ // If the address spaces don't match, don't eliminate the bitcast, which is
+ // required for changing types.
+ if (SrcPTy->getAddressSpace() != DstPTy->getAddressSpace())
+ return 0;
+
+ // If we are casting a alloca to a pointer to a type of the same
+ // size, rewrite the allocation instruction to allocate the "right" type.
+ // There is no need to modify malloc calls because it is their bitcast that
+ // needs to be cleaned up.
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(Src))
+ if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
+ return V;
+
+ // If the source and destination are pointers, and this cast is equivalent
+ // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
+ // This can enhance SROA and other transforms that want type-safe pointers.
+ Constant *ZeroUInt = Constant::getNullValue(Type::getInt32Ty(*Context));
+ unsigned NumZeros = 0;
+ while (SrcElTy != DstElTy &&
+ isa<CompositeType>(SrcElTy) && !isa<PointerType>(SrcElTy) &&
+ SrcElTy->getNumContainedTypes() /* not "{}" */) {
+ SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
+ ++NumZeros;
+ }
+
+ // If we found a path from the src to dest, create the getelementptr now.
+ if (SrcElTy == DstElTy) {
+ SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
+ return GetElementPtrInst::CreateInBounds(Src, Idxs.begin(), Idxs.end(), "",
+ ((Instruction*) NULL));
+ }
+ }
+
+ if (const VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
+ if (DestVTy->getNumElements() == 1) {
+ if (!isa<VectorType>(SrcTy)) {
+ Value *Elem = Builder->CreateBitCast(Src, DestVTy->getElementType());
+ return InsertElementInst::Create(UndefValue::get(DestTy), Elem,
+ Constant::getNullValue(Type::getInt32Ty(*Context)));
+ }
+ // FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
+ }
+ }
+
+ if (const VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) {
+ if (SrcVTy->getNumElements() == 1) {
+ if (!isa<VectorType>(DestTy)) {
+ Value *Elem =
+ Builder->CreateExtractElement(Src,
+ Constant::getNullValue(Type::getInt32Ty(*Context)));
+ return CastInst::Create(Instruction::BitCast, Elem, DestTy);
+ }
+ }
+ }
+
+ if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
+ if (SVI->hasOneUse()) {
+ // Okay, we have (bitconvert (shuffle ..)). Check to see if this is
+ // a bitconvert to a vector with the same # elts.
+ if (isa<VectorType>(DestTy) &&
+ cast<VectorType>(DestTy)->getNumElements() ==
+ SVI->getType()->getNumElements() &&
+ SVI->getType()->getNumElements() ==
+ cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements()) {
+ CastInst *Tmp;
+ // If either of the operands is a cast from CI.getType(), then
+ // evaluating the shuffle in the casted destination's type will allow
+ // us to eliminate at least one cast.
+ if (((Tmp = dyn_cast<CastInst>(SVI->getOperand(0))) &&
+ Tmp->getOperand(0)->getType() == DestTy) ||
+ ((Tmp = dyn_cast<CastInst>(SVI->getOperand(1))) &&
+ Tmp->getOperand(0)->getType() == DestTy)) {
+ Value *LHS = Builder->CreateBitCast(SVI->getOperand(0), DestTy);
+ Value *RHS = Builder->CreateBitCast(SVI->getOperand(1), DestTy);
+ // Return a new shuffle vector. Use the same element ID's, as we
+ // know the vector types match #elts.
+ return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
+ }
+ }
+ }
+ }
+ return 0;
+}
+
+/// GetSelectFoldableOperands - We want to turn code that looks like this:
+/// %C = or %A, %B
+/// %D = select %cond, %C, %A
+/// into:
+/// %C = select %cond, %B, 0
+/// %D = or %A, %C
+///
+/// Assuming that the specified instruction is an operand to the select, return
+/// a bitmask indicating which operands of this instruction are foldable if they
+/// equal the other incoming value of the select.
+///
+static unsigned GetSelectFoldableOperands(Instruction *I) {
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Mul:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ return 3; // Can fold through either operand.
+ case Instruction::Sub: // Can only fold on the amount subtracted.
+ case Instruction::Shl: // Can only fold on the shift amount.
+ case Instruction::LShr:
+ case Instruction::AShr:
+ return 1;
+ default:
+ return 0; // Cannot fold
+ }
+}
+
+/// GetSelectFoldableConstant - For the same transformation as the previous
+/// function, return the identity constant that goes into the select.
+static Constant *GetSelectFoldableConstant(Instruction *I,
+ LLVMContext *Context) {
+ switch (I->getOpcode()) {
+ default: llvm_unreachable("This cannot happen!");
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Or:
+ case Instruction::Xor:
+ case Instruction::Shl:
+ case Instruction::LShr:
+ case Instruction::AShr:
+ return Constant::getNullValue(I->getType());
+ case Instruction::And:
+ return Constant::getAllOnesValue(I->getType());
+ case Instruction::Mul:
+ return ConstantInt::get(I->getType(), 1);
+ }
+}
+
+/// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
+/// have the same opcode and only one use each. Try to simplify this.
+Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
+ Instruction *FI) {
+ if (TI->getNumOperands() == 1) {
+ // If this is a non-volatile load or a cast from the same type,
+ // merge.
+ if (TI->isCast()) {
+ if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
+ return 0;
+ } else {
+ return 0; // unknown unary op.
+ }
+
+ // Fold this by inserting a select from the input values.
+ SelectInst *NewSI = SelectInst::Create(SI.getCondition(), TI->getOperand(0),
+ FI->getOperand(0), SI.getName()+".v");
+ InsertNewInstBefore(NewSI, SI);
+ return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
+ TI->getType());
+ }
+
+ // Only handle binary operators here.
+ if (!isa<BinaryOperator>(TI))
+ return 0;
+
+ // Figure out if the operations have any operands in common.
+ Value *MatchOp, *OtherOpT, *OtherOpF;
+ bool MatchIsOpZero;
+ if (TI->getOperand(0) == FI->getOperand(0)) {
+ MatchOp = TI->getOperand(0);
+ OtherOpT = TI->getOperand(1);
+ OtherOpF = FI->getOperand(1);
+ MatchIsOpZero = true;
+ } else if (TI->getOperand(1) == FI->getOperand(1)) {
+ MatchOp = TI->getOperand(1);
+ OtherOpT = TI->getOperand(0);
+ OtherOpF = FI->getOperand(0);
+ MatchIsOpZero = false;
+ } else if (!TI->isCommutative()) {
+ return 0;
+ } else if (TI->getOperand(0) == FI->getOperand(1)) {
+ MatchOp = TI->getOperand(0);
+ OtherOpT = TI->getOperand(1);
+ OtherOpF = FI->getOperand(0);
+ MatchIsOpZero = true;
+ } else if (TI->getOperand(1) == FI->getOperand(0)) {
+ MatchOp = TI->getOperand(1);
+ OtherOpT = TI->getOperand(0);
+ OtherOpF = FI->getOperand(1);
+ MatchIsOpZero = true;
+ } else {
+ return 0;
+ }
+
+ // If we reach here, they do have operations in common.
+ SelectInst *NewSI = SelectInst::Create(SI.getCondition(), OtherOpT,
+ OtherOpF, SI.getName()+".v");
+ InsertNewInstBefore(NewSI, SI);
+
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
+ if (MatchIsOpZero)
+ return BinaryOperator::Create(BO->getOpcode(), MatchOp, NewSI);
+ else
+ return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp);
+ }
+ llvm_unreachable("Shouldn't get here");
+ return 0;
+}
+
+static bool isSelect01(Constant *C1, Constant *C2) {
+ ConstantInt *C1I = dyn_cast<ConstantInt>(C1);
+ if (!C1I)
+ return false;
+ ConstantInt *C2I = dyn_cast<ConstantInt>(C2);
+ if (!C2I)
+ return false;
+ return (C1I->isZero() || C1I->isOne()) && (C2I->isZero() || C2I->isOne());
+}
+
+/// FoldSelectIntoOp - Try fold the select into one of the operands to
+/// facilitate further optimization.
+Instruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal,
+ Value *FalseVal) {
+ // See the comment above GetSelectFoldableOperands for a description of the
+ // transformation we are doing here.
+ if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) {
+ if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
+ !isa<Constant>(FalseVal)) {
+ if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
+ unsigned OpToFold = 0;
+ if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
+ OpToFold = 1;
+ } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
+ OpToFold = 2;
+ }
+
+ if (OpToFold) {
+ Constant *C = GetSelectFoldableConstant(TVI, Context);
+ Value *OOp = TVI->getOperand(2-OpToFold);
+ // Avoid creating select between 2 constants unless it's selecting
+ // between 0 and 1.
+ if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
+ Instruction *NewSel = SelectInst::Create(SI.getCondition(), OOp, C);
+ InsertNewInstBefore(NewSel, SI);
+ NewSel->takeName(TVI);
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
+ return BinaryOperator::Create(BO->getOpcode(), FalseVal, NewSel);
+ llvm_unreachable("Unknown instruction!!");
+ }
+ }
+ }
+ }
+ }
+
+ if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) {
+ if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
+ !isa<Constant>(TrueVal)) {
+ if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
+ unsigned OpToFold = 0;
+ if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
+ OpToFold = 1;
+ } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
+ OpToFold = 2;
+ }
+
+ if (OpToFold) {
+ Constant *C = GetSelectFoldableConstant(FVI, Context);
+ Value *OOp = FVI->getOperand(2-OpToFold);
+ // Avoid creating select between 2 constants unless it's selecting
+ // between 0 and 1.
+ if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
+ Instruction *NewSel = SelectInst::Create(SI.getCondition(), C, OOp);
+ InsertNewInstBefore(NewSel, SI);
+ NewSel->takeName(FVI);
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
+ return BinaryOperator::Create(BO->getOpcode(), TrueVal, NewSel);
+ llvm_unreachable("Unknown instruction!!");
+ }
+ }
+ }
+ }
+ }
+
+ return 0;
+}
+
+/// visitSelectInstWithICmp - Visit a SelectInst that has an
+/// ICmpInst as its first operand.
+///
+Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI,
+ ICmpInst *ICI) {
+ bool Changed = false;
+ ICmpInst::Predicate Pred = ICI->getPredicate();
+ Value *CmpLHS = ICI->getOperand(0);
+ Value *CmpRHS = ICI->getOperand(1);
+ Value *TrueVal = SI.getTrueValue();
+ Value *FalseVal = SI.getFalseValue();
+
+ // Check cases where the comparison is with a constant that
+ // can be adjusted to fit the min/max idiom. We may edit ICI in
+ // place here, so make sure the select is the only user.
+ if (ICI->hasOneUse())
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) {
+ switch (Pred) {
+ default: break;
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_SLT: {
+ // X < MIN ? T : F --> F
+ if (CI->isMinValue(Pred == ICmpInst::ICMP_SLT))
+ return ReplaceInstUsesWith(SI, FalseVal);
+ // X < C ? X : C-1 --> X > C-1 ? C-1 : X
+ Constant *AdjustedRHS = SubOne(CI);
+ if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
+ (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
+ Pred = ICmpInst::getSwappedPredicate(Pred);
+ CmpRHS = AdjustedRHS;
+ std::swap(FalseVal, TrueVal);
+ ICI->setPredicate(Pred);
+ ICI->setOperand(1, CmpRHS);
+ SI.setOperand(1, TrueVal);
+ SI.setOperand(2, FalseVal);
+ Changed = true;
+ }
+ break;
+ }
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_SGT: {
+ // X > MAX ? T : F --> F
+ if (CI->isMaxValue(Pred == ICmpInst::ICMP_SGT))
+ return ReplaceInstUsesWith(SI, FalseVal);
+ // X > C ? X : C+1 --> X < C+1 ? C+1 : X
+ Constant *AdjustedRHS = AddOne(CI);
+ if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
+ (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
+ Pred = ICmpInst::getSwappedPredicate(Pred);
+ CmpRHS = AdjustedRHS;
+ std::swap(FalseVal, TrueVal);
+ ICI->setPredicate(Pred);
+ ICI->setOperand(1, CmpRHS);
+ SI.setOperand(1, TrueVal);
+ SI.setOperand(2, FalseVal);
+ Changed = true;
+ }
+ break;
+ }
+ }
+
+ // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed
+ // (x >s -1) ? -1 : 0 -> ashr x, 31 -> all ones if not signed
+ CmpInst::Predicate Pred = CmpInst::BAD_ICMP_PREDICATE;
+ if (match(TrueVal, m_ConstantInt<-1>()) &&
+ match(FalseVal, m_ConstantInt<0>()))
+ Pred = ICI->getPredicate();
+ else if (match(TrueVal, m_ConstantInt<0>()) &&
+ match(FalseVal, m_ConstantInt<-1>()))
+ Pred = CmpInst::getInversePredicate(ICI->getPredicate());
+
+ if (Pred != CmpInst::BAD_ICMP_PREDICATE) {
+ // If we are just checking for a icmp eq of a single bit and zext'ing it
+ // to an integer, then shift the bit to the appropriate place and then
+ // cast to integer to avoid the comparison.
+ const APInt &Op1CV = CI->getValue();
+
+ // sext (x <s 0) to i32 --> x>>s31 true if signbit set.
+ // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear.
+ if ((Pred == ICmpInst::ICMP_SLT && Op1CV == 0) ||
+ (Pred == ICmpInst::ICMP_SGT && Op1CV.isAllOnesValue())) {
+ Value *In = ICI->getOperand(0);
+ Value *Sh = ConstantInt::get(In->getType(),
+ In->getType()->getScalarSizeInBits()-1);
+ In = InsertNewInstBefore(BinaryOperator::CreateAShr(In, Sh,
+ In->getName()+".lobit"),
+ *ICI);
+ if (In->getType() != SI.getType())
+ In = CastInst::CreateIntegerCast(In, SI.getType(),
+ true/*SExt*/, "tmp", ICI);
+
+ if (Pred == ICmpInst::ICMP_SGT)
+ In = InsertNewInstBefore(BinaryOperator::CreateNot(In,
+ In->getName()+".not"), *ICI);
+
+ return ReplaceInstUsesWith(SI, In);
+ }
+ }
+ }
+
+ if (CmpLHS == TrueVal && CmpRHS == FalseVal) {
+ // Transform (X == Y) ? X : Y -> Y
+ if (Pred == ICmpInst::ICMP_EQ)
+ return ReplaceInstUsesWith(SI, FalseVal);
+ // Transform (X != Y) ? X : Y -> X
+ if (Pred == ICmpInst::ICMP_NE)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
+
+ } else if (CmpLHS == FalseVal && CmpRHS == TrueVal) {
+ // Transform (X == Y) ? Y : X -> X
+ if (Pred == ICmpInst::ICMP_EQ)
+ return ReplaceInstUsesWith(SI, FalseVal);
+ // Transform (X != Y) ? Y : X -> Y
+ if (Pred == ICmpInst::ICMP_NE)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
+ }
+ return Changed ? &SI : 0;
+}
+
+
+/// CanSelectOperandBeMappingIntoPredBlock - SI is a select whose condition is a
+/// PHI node (but the two may be in different blocks). See if the true/false
+/// values (V) are live in all of the predecessor blocks of the PHI. For
+/// example, cases like this cannot be mapped:
+///
+/// X = phi [ C1, BB1], [C2, BB2]
+/// Y = add
+/// Z = select X, Y, 0
+///
+/// because Y is not live in BB1/BB2.
+///
+static bool CanSelectOperandBeMappingIntoPredBlock(const Value *V,
+ const SelectInst &SI) {
+ // If the value is a non-instruction value like a constant or argument, it
+ // can always be mapped.
+ const Instruction *I = dyn_cast<Instruction>(V);
+ if (I == 0) return true;
+
+ // If V is a PHI node defined in the same block as the condition PHI, we can
+ // map the arguments.
+ const PHINode *CondPHI = cast<PHINode>(SI.getCondition());
+
+ if (const PHINode *VP = dyn_cast<PHINode>(I))
+ if (VP->getParent() == CondPHI->getParent())
+ return true;
+
+ // Otherwise, if the PHI and select are defined in the same block and if V is
+ // defined in a different block, then we can transform it.
+ if (SI.getParent() == CondPHI->getParent() &&
+ I->getParent() != CondPHI->getParent())
+ return true;
+
+ // Otherwise we have a 'hard' case and we can't tell without doing more
+ // detailed dominator based analysis, punt.
+ return false;
+}
+
+/// FoldSPFofSPF - We have an SPF (e.g. a min or max) of an SPF of the form:
+/// SPF2(SPF1(A, B), C)
+Instruction *InstCombiner::FoldSPFofSPF(Instruction *Inner,
+ SelectPatternFlavor SPF1,
+ Value *A, Value *B,
+ Instruction &Outer,
+ SelectPatternFlavor SPF2, Value *C) {
+ if (C == A || C == B) {
+ // MAX(MAX(A, B), B) -> MAX(A, B)
+ // MIN(MIN(a, b), a) -> MIN(a, b)
+ if (SPF1 == SPF2)
+ return ReplaceInstUsesWith(Outer, Inner);
+
+ // MAX(MIN(a, b), a) -> a
+ // MIN(MAX(a, b), a) -> a
+ if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) ||
+ (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) ||
+ (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) ||
+ (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN))
+ return ReplaceInstUsesWith(Outer, C);
+ }
+
+ // TODO: MIN(MIN(A, 23), 97)
+ return 0;
+}
+
+
+
+
+Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
+ Value *CondVal = SI.getCondition();
+ Value *TrueVal = SI.getTrueValue();
+ Value *FalseVal = SI.getFalseValue();
+
+ // select true, X, Y -> X
+ // select false, X, Y -> Y
+ if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal))
+ return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal);
+
+ // select C, X, X -> X
+ if (TrueVal == FalseVal)
+ return ReplaceInstUsesWith(SI, TrueVal);
+
+ if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
+ return ReplaceInstUsesWith(SI, FalseVal);
+ if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
+ return ReplaceInstUsesWith(SI, TrueVal);
+ if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
+ if (isa<Constant>(TrueVal))
+ return ReplaceInstUsesWith(SI, TrueVal);
+ else
+ return ReplaceInstUsesWith(SI, FalseVal);
+ }
+
+ if (SI.getType() == Type::getInt1Ty(*Context)) {
+ if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) {
+ if (C->getZExtValue()) {
+ // Change: A = select B, true, C --> A = or B, C
+ return BinaryOperator::CreateOr(CondVal, FalseVal);
+ } else {
+ // Change: A = select B, false, C --> A = and !B, C
+ Value *NotCond =
+ InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
+ "not."+CondVal->getName()), SI);
+ return BinaryOperator::CreateAnd(NotCond, FalseVal);
+ }
+ } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
+ if (C->getZExtValue() == false) {
+ // Change: A = select B, C, false --> A = and B, C
+ return BinaryOperator::CreateAnd(CondVal, TrueVal);
+ } else {
+ // Change: A = select B, C, true --> A = or !B, C
+ Value *NotCond =
+ InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
+ "not."+CondVal->getName()), SI);
+ return BinaryOperator::CreateOr(NotCond, TrueVal);
+ }
+ }
+
+ // select a, b, a -> a&b
+ // select a, a, b -> a|b
+ if (CondVal == TrueVal)
+ return BinaryOperator::CreateOr(CondVal, FalseVal);
+ else if (CondVal == FalseVal)
+ return BinaryOperator::CreateAnd(CondVal, TrueVal);
+ }
+
+ // Selecting between two integer constants?
+ if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
+ if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
+ // select C, 1, 0 -> zext C to int
+ if (FalseValC->isZero() && TrueValC->getValue() == 1) {
+ return CastInst::Create(Instruction::ZExt, CondVal, SI.getType());
+ } else if (TrueValC->isZero() && FalseValC->getValue() == 1) {
+ // select C, 0, 1 -> zext !C to int
+ Value *NotCond =
+ InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
+ "not."+CondVal->getName()), SI);
+ return CastInst::Create(Instruction::ZExt, NotCond, SI.getType());
+ }
+
+ if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) {
+ // If one of the constants is zero (we know they can't both be) and we
+ // have an icmp instruction with zero, and we have an 'and' with the
+ // non-constant value, eliminate this whole mess. This corresponds to
+ // cases like this: ((X & 27) ? 27 : 0)
+ if (TrueValC->isZero() || FalseValC->isZero())
+ if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
+ cast<Constant>(IC->getOperand(1))->isNullValue())
+ if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
+ if (ICA->getOpcode() == Instruction::And &&
+ isa<ConstantInt>(ICA->getOperand(1)) &&
+ (ICA->getOperand(1) == TrueValC ||
+ ICA->getOperand(1) == FalseValC) &&
+ isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
+ // Okay, now we know that everything is set up, we just don't
+ // know whether we have a icmp_ne or icmp_eq and whether the
+ // true or false val is the zero.
+ bool ShouldNotVal = !TrueValC->isZero();
+ ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
+ Value *V = ICA;
+ if (ShouldNotVal)
+ V = InsertNewInstBefore(BinaryOperator::Create(
+ Instruction::Xor, V, ICA->getOperand(1)), SI);
+ return ReplaceInstUsesWith(SI, V);
+ }
+ }
+ }
+
+ // See if we are selecting two values based on a comparison of the two values.
+ if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
+ if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
+ // Transform (X == Y) ? X : Y -> Y
+ if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
+ // This is not safe in general for floating point:
+ // consider X== -0, Y== +0.
+ // It becomes safe if either operand is a nonzero constant.
+ ConstantFP *CFPt, *CFPf;
+ if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
+ !CFPt->getValueAPF().isZero()) ||
+ ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
+ !CFPf->getValueAPF().isZero()))
+ return ReplaceInstUsesWith(SI, FalseVal);
+ }
+ // Transform (X != Y) ? X : Y -> X
+ if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ // NOTE: if we wanted to, this is where to detect MIN/MAX
+
+ } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
+ // Transform (X == Y) ? Y : X -> X
+ if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
+ // This is not safe in general for floating point:
+ // consider X== -0, Y== +0.
+ // It becomes safe if either operand is a nonzero constant.
+ ConstantFP *CFPt, *CFPf;
+ if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
+ !CFPt->getValueAPF().isZero()) ||
+ ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
+ !CFPf->getValueAPF().isZero()))
+ return ReplaceInstUsesWith(SI, FalseVal);
+ }
+ // Transform (X != Y) ? Y : X -> Y
+ if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ // NOTE: if we wanted to, this is where to detect MIN/MAX
+ }
+ // NOTE: if we wanted to, this is where to detect ABS
+ }
+
+ // See if we are selecting two values based on a comparison of the two values.
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
+ if (Instruction *Result = visitSelectInstWithICmp(SI, ICI))
+ return Result;
+
+ if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
+ if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
+ if (TI->hasOneUse() && FI->hasOneUse()) {
+ Instruction *AddOp = 0, *SubOp = 0;
+
+ // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
+ if (TI->getOpcode() == FI->getOpcode())
+ if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
+ return IV;
+
+ // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
+ // even legal for FP.
+ if ((TI->getOpcode() == Instruction::Sub &&
+ FI->getOpcode() == Instruction::Add) ||
+ (TI->getOpcode() == Instruction::FSub &&
+ FI->getOpcode() == Instruction::FAdd)) {
+ AddOp = FI; SubOp = TI;
+ } else if ((FI->getOpcode() == Instruction::Sub &&
+ TI->getOpcode() == Instruction::Add) ||
+ (FI->getOpcode() == Instruction::FSub &&
+ TI->getOpcode() == Instruction::FAdd)) {
+ AddOp = TI; SubOp = FI;
+ }
+
+ if (AddOp) {
+ Value *OtherAddOp = 0;
+ if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
+ OtherAddOp = AddOp->getOperand(1);
+ } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
+ OtherAddOp = AddOp->getOperand(0);
+ }
+
+ if (OtherAddOp) {
+ // So at this point we know we have (Y -> OtherAddOp):
+ // select C, (add X, Y), (sub X, Z)
+ Value *NegVal; // Compute -Z
+ if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
+ NegVal = ConstantExpr::getNeg(C);
+ } else {
+ NegVal = InsertNewInstBefore(
+ BinaryOperator::CreateNeg(SubOp->getOperand(1),
+ "tmp"), SI);
+ }
+
+ Value *NewTrueOp = OtherAddOp;
+ Value *NewFalseOp = NegVal;
+ if (AddOp != TI)
+ std::swap(NewTrueOp, NewFalseOp);
+ Instruction *NewSel =
+ SelectInst::Create(CondVal, NewTrueOp,
+ NewFalseOp, SI.getName() + ".p");
+
+ NewSel = InsertNewInstBefore(NewSel, SI);
+ return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
+ }
+ }
+ }
+
+ // See if we can fold the select into one of our operands.
+ if (SI.getType()->isInteger()) {
+ if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal))
+ return FoldI;
+
+ // MAX(MAX(a, b), a) -> MAX(a, b)
+ // MIN(MIN(a, b), a) -> MIN(a, b)
+ // MAX(MIN(a, b), a) -> a
+ // MIN(MAX(a, b), a) -> a
+ Value *LHS, *RHS, *LHS2, *RHS2;
+ if (SelectPatternFlavor SPF = MatchSelectPattern(&SI, LHS, RHS)) {
+ if (SelectPatternFlavor SPF2 = MatchSelectPattern(LHS, LHS2, RHS2))
+ if (Instruction *R = FoldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2,
+ SI, SPF, RHS))
+ return R;
+ if (SelectPatternFlavor SPF2 = MatchSelectPattern(RHS, LHS2, RHS2))
+ if (Instruction *R = FoldSPFofSPF(cast<Instruction>(RHS),SPF2,LHS2,RHS2,
+ SI, SPF, LHS))
+ return R;
+ }
+
+ // TODO.
+ // ABS(-X) -> ABS(X)
+ // ABS(ABS(X)) -> ABS(X)
+ }
+
+ // See if we can fold the select into a phi node if the condition is a select.
+ if (isa<PHINode>(SI.getCondition()))
+ // The true/false values have to be live in the PHI predecessor's blocks.
+ if (CanSelectOperandBeMappingIntoPredBlock(TrueVal, SI) &&
+ CanSelectOperandBeMappingIntoPredBlock(FalseVal, SI))
+ if (Instruction *NV = FoldOpIntoPhi(SI))
+ return NV;
+
+ if (BinaryOperator::isNot(CondVal)) {
+ SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
+ SI.setOperand(1, FalseVal);
+ SI.setOperand(2, TrueVal);
+ return &SI;
+ }
+
+ return 0;
+}
+
+/// EnforceKnownAlignment - If the specified pointer points to an object that
+/// we control, modify the object's alignment to PrefAlign. This isn't
+/// often possible though. If alignment is important, a more reliable approach
+/// is to simply align all global variables and allocation instructions to
+/// their preferred alignment from the beginning.
+///
+static unsigned EnforceKnownAlignment(Value *V,
+ unsigned Align, unsigned PrefAlign) {
+
+ User *U = dyn_cast<User>(V);
+ if (!U) return Align;
+
+ switch (Operator::getOpcode(U)) {
+ default: break;
+ case Instruction::BitCast:
+ return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
+ case Instruction::GetElementPtr: {
+ // If all indexes are zero, it is just the alignment of the base pointer.
+ bool AllZeroOperands = true;
+ for (User::op_iterator i = U->op_begin() + 1, e = U->op_end(); i != e; ++i)
+ if (!isa<Constant>(*i) ||
+ !cast<Constant>(*i)->isNullValue()) {
+ AllZeroOperands = false;
+ break;
+ }
+
+ if (AllZeroOperands) {
+ // Treat this like a bitcast.
+ return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
+ }
+ break;
+ }
+ }
+
+ if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
+ // If there is a large requested alignment and we can, bump up the alignment
+ // of the global.
+ if (!GV->isDeclaration()) {
+ if (GV->getAlignment() >= PrefAlign)
+ Align = GV->getAlignment();
+ else {
+ GV->setAlignment(PrefAlign);
+ Align = PrefAlign;
+ }
+ }
+ } else if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
+ // If there is a requested alignment and if this is an alloca, round up.
+ if (AI->getAlignment() >= PrefAlign)
+ Align = AI->getAlignment();
+ else {
+ AI->setAlignment(PrefAlign);
+ Align = PrefAlign;
+ }
+ }
+
+ return Align;
+}
+
+/// GetOrEnforceKnownAlignment - If the specified pointer has an alignment that
+/// we can determine, return it, otherwise return 0. If PrefAlign is specified,
+/// and it is more than the alignment of the ultimate object, see if we can
+/// increase the alignment of the ultimate object, making this check succeed.
+unsigned InstCombiner::GetOrEnforceKnownAlignment(Value *V,
+ unsigned PrefAlign) {
+ unsigned BitWidth = TD ? TD->getTypeSizeInBits(V->getType()) :
+ sizeof(PrefAlign) * CHAR_BIT;
+ APInt Mask = APInt::getAllOnesValue(BitWidth);
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ ComputeMaskedBits(V, Mask, KnownZero, KnownOne);
+ unsigned TrailZ = KnownZero.countTrailingOnes();
+ unsigned Align = 1u << std::min(BitWidth - 1, TrailZ);
+
+ if (PrefAlign > Align)
+ Align = EnforceKnownAlignment(V, Align, PrefAlign);
+
+ // We don't need to make any adjustment.
+ return Align;
+}
+
+Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
+ unsigned DstAlign = GetOrEnforceKnownAlignment(MI->getOperand(1));
+ unsigned SrcAlign = GetOrEnforceKnownAlignment(MI->getOperand(2));
+ unsigned MinAlign = std::min(DstAlign, SrcAlign);
+ unsigned CopyAlign = MI->getAlignment();
+
+ if (CopyAlign < MinAlign) {
+ MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
+ MinAlign, false));
+ return MI;
+ }
+
+ // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
+ // load/store.
+ ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getOperand(3));
+ if (MemOpLength == 0) return 0;
+
+ // Source and destination pointer types are always "i8*" for intrinsic. See
+ // if the size is something we can handle with a single primitive load/store.
+ // A single load+store correctly handles overlapping memory in the memmove
+ // case.
+ unsigned Size = MemOpLength->getZExtValue();
+ if (Size == 0) return MI; // Delete this mem transfer.
+
+ if (Size > 8 || (Size&(Size-1)))
+ return 0; // If not 1/2/4/8 bytes, exit.
+
+ // Use an integer load+store unless we can find something better.
+ Type *NewPtrTy =
+ PointerType::getUnqual(IntegerType::get(*Context, Size<<3));
+
+ // Memcpy forces the use of i8* for the source and destination. That means
+ // that if you're using memcpy to move one double around, you'll get a cast
+ // from double* to i8*. We'd much rather use a double load+store rather than
+ // an i64 load+store, here because this improves the odds that the source or
+ // dest address will be promotable. See if we can find a better type than the
+ // integer datatype.
+ if (Value *Op = getBitCastOperand(MI->getOperand(1))) {
+ const Type *SrcETy = cast<PointerType>(Op->getType())->getElementType();
+ if (TD && SrcETy->isSized() && TD->getTypeStoreSize(SrcETy) == Size) {
+ // The SrcETy might be something like {{{double}}} or [1 x double]. Rip
+ // down through these levels if so.
+ while (!SrcETy->isSingleValueType()) {
+ if (const StructType *STy = dyn_cast<StructType>(SrcETy)) {
+ if (STy->getNumElements() == 1)
+ SrcETy = STy->getElementType(0);
+ else
+ break;
+ } else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcETy)) {
+ if (ATy->getNumElements() == 1)
+ SrcETy = ATy->getElementType();
+ else
+ break;
+ } else
+ break;
+ }
+
+ if (SrcETy->isSingleValueType())
+ NewPtrTy = PointerType::getUnqual(SrcETy);
+ }
+ }
+
+
+ // If the memcpy/memmove provides better alignment info than we can
+ // infer, use it.
+ SrcAlign = std::max(SrcAlign, CopyAlign);
+ DstAlign = std::max(DstAlign, CopyAlign);
+
+ Value *Src = Builder->CreateBitCast(MI->getOperand(2), NewPtrTy);
+ Value *Dest = Builder->CreateBitCast(MI->getOperand(1), NewPtrTy);
+ Instruction *L = new LoadInst(Src, "tmp", false, SrcAlign);
+ InsertNewInstBefore(L, *MI);
+ InsertNewInstBefore(new StoreInst(L, Dest, false, DstAlign), *MI);
+
+ // Set the size of the copy to 0, it will be deleted on the next iteration.
+ MI->setOperand(3, Constant::getNullValue(MemOpLength->getType()));
+ return MI;
+}
+
+Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) {
+ unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest());
+ if (MI->getAlignment() < Alignment) {
+ MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
+ Alignment, false));
+ return MI;
+ }
+
+ // Extract the length and alignment and fill if they are constant.
+ ConstantInt *LenC = dyn_cast<ConstantInt>(MI->getLength());
+ ConstantInt *FillC = dyn_cast<ConstantInt>(MI->getValue());
+ if (!LenC || !FillC || FillC->getType() != Type::getInt8Ty(*Context))
+ return 0;
+ uint64_t Len = LenC->getZExtValue();
+ Alignment = MI->getAlignment();
+
+ // If the length is zero, this is a no-op
+ if (Len == 0) return MI; // memset(d,c,0,a) -> noop
+
+ // memset(s,c,n) -> store s, c (for n=1,2,4,8)
+ if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) {
+ const Type *ITy = IntegerType::get(*Context, Len*8); // n=1 -> i8.
+
+ Value *Dest = MI->getDest();
+ Dest = Builder->CreateBitCast(Dest, PointerType::getUnqual(ITy));
+
+ // Alignment 0 is identity for alignment 1 for memset, but not store.
+ if (Alignment == 0) Alignment = 1;
+
+ // Extract the fill value and store.
+ uint64_t Fill = FillC->getZExtValue()*0x0101010101010101ULL;
+ InsertNewInstBefore(new StoreInst(ConstantInt::get(ITy, Fill),
+ Dest, false, Alignment), *MI);
+
+ // Set the size of the copy to 0, it will be deleted on the next iteration.
+ MI->setLength(Constant::getNullValue(LenC->getType()));
+ return MI;
+ }
+
+ return 0;
+}
+
+
+/// visitCallInst - CallInst simplification. This mostly only handles folding
+/// of intrinsic instructions. For normal calls, it allows visitCallSite to do
+/// the heavy lifting.
+///
+Instruction *InstCombiner::visitCallInst(CallInst &CI) {
+ if (isFreeCall(&CI))
+ return visitFree(CI);
+
+ // If the caller function is nounwind, mark the call as nounwind, even if the
+ // callee isn't.
+ if (CI.getParent()->getParent()->doesNotThrow() &&
+ !CI.doesNotThrow()) {
+ CI.setDoesNotThrow();
+ return &CI;
+ }
+
+ IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
+ if (!II) return visitCallSite(&CI);
+
+ // Intrinsics cannot occur in an invoke, so handle them here instead of in
+ // visitCallSite.
+ if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
+ bool Changed = false;
+
+ // memmove/cpy/set of zero bytes is a noop.
+ if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
+ if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
+
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
+ if (CI->getZExtValue() == 1) {
+ // Replace the instruction with just byte operations. We would
+ // transform other cases to loads/stores, but we don't know if
+ // alignment is sufficient.
+ }
+ }
+
+ // If we have a memmove and the source operation is a constant global,
+ // then the source and dest pointers can't alias, so we can change this
+ // into a call to memcpy.
+ if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI)) {
+ if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
+ if (GVSrc->isConstant()) {
+ Module *M = CI.getParent()->getParent()->getParent();
+ Intrinsic::ID MemCpyID = Intrinsic::memcpy;
+ const Type *Tys[1];
+ Tys[0] = CI.getOperand(3)->getType();
+ CI.setOperand(0,
+ Intrinsic::getDeclaration(M, MemCpyID, Tys, 1));
+ Changed = true;
+ }
+ }
+
+ if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
+ // memmove(x,x,size) -> noop.
+ if (MTI->getSource() == MTI->getDest())
+ return EraseInstFromFunction(CI);
+ }
+
+ // If we can determine a pointer alignment that is bigger than currently
+ // set, update the alignment.
+ if (isa<MemTransferInst>(MI)) {
+ if (Instruction *I = SimplifyMemTransfer(MI))
+ return I;
+ } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(MI)) {
+ if (Instruction *I = SimplifyMemSet(MSI))
+ return I;
+ }
+
+ if (Changed) return II;
+ }
+
+ switch (II->getIntrinsicID()) {
+ default: break;
+ case Intrinsic::bswap:
+ // bswap(bswap(x)) -> x
+ if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(II->getOperand(1)))
+ if (Operand->getIntrinsicID() == Intrinsic::bswap)
+ return ReplaceInstUsesWith(CI, Operand->getOperand(1));
+
+ // bswap(trunc(bswap(x))) -> trunc(lshr(x, c))
+ if (TruncInst *TI = dyn_cast<TruncInst>(II->getOperand(1))) {
+ if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(TI->getOperand(0)))
+ if (Operand->getIntrinsicID() == Intrinsic::bswap) {
+ unsigned C = Operand->getType()->getPrimitiveSizeInBits() -
+ TI->getType()->getPrimitiveSizeInBits();
+ Value *CV = ConstantInt::get(Operand->getType(), C);
+ Value *V = Builder->CreateLShr(Operand->getOperand(1), CV);
+ return new TruncInst(V, TI->getType());
+ }
+ }
+
+ break;
+ case Intrinsic::powi:
+ if (ConstantInt *Power = dyn_cast<ConstantInt>(II->getOperand(2))) {
+ // powi(x, 0) -> 1.0
+ if (Power->isZero())
+ return ReplaceInstUsesWith(CI, ConstantFP::get(CI.getType(), 1.0));
+ // powi(x, 1) -> x
+ if (Power->isOne())
+ return ReplaceInstUsesWith(CI, II->getOperand(1));
+ // powi(x, -1) -> 1/x
+ if (Power->isAllOnesValue())
+ return BinaryOperator::CreateFDiv(ConstantFP::get(CI.getType(), 1.0),
+ II->getOperand(1));
+ }
+ break;
+
+ case Intrinsic::uadd_with_overflow: {
+ Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
+ const IntegerType *IT = cast<IntegerType>(II->getOperand(1)->getType());
+ uint32_t BitWidth = IT->getBitWidth();
+ APInt Mask = APInt::getSignBit(BitWidth);
+ APInt LHSKnownZero(BitWidth, 0);
+ APInt LHSKnownOne(BitWidth, 0);
+ ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
+ bool LHSKnownNegative = LHSKnownOne[BitWidth - 1];
+ bool LHSKnownPositive = LHSKnownZero[BitWidth - 1];
+
+ if (LHSKnownNegative || LHSKnownPositive) {
+ APInt RHSKnownZero(BitWidth, 0);
+ APInt RHSKnownOne(BitWidth, 0);
+ ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
+ bool RHSKnownNegative = RHSKnownOne[BitWidth - 1];
+ bool RHSKnownPositive = RHSKnownZero[BitWidth - 1];
+ if (LHSKnownNegative && RHSKnownNegative) {
+ // The sign bit is set in both cases: this MUST overflow.
+ // Create a simple add instruction, and insert it into the struct.
+ Instruction *Add = BinaryOperator::CreateAdd(LHS, RHS, "", &CI);
+ Worklist.Add(Add);
+ Constant *V[] = {
+ UndefValue::get(LHS->getType()), ConstantInt::getTrue(*Context)
+ };
+ Constant *Struct = ConstantStruct::get(*Context, V, 2, false);
+ return InsertValueInst::Create(Struct, Add, 0);
+ }
+
+ if (LHSKnownPositive && RHSKnownPositive) {
+ // The sign bit is clear in both cases: this CANNOT overflow.
+ // Create a simple add instruction, and insert it into the struct.
+ Instruction *Add = BinaryOperator::CreateNUWAdd(LHS, RHS, "", &CI);
+ Worklist.Add(Add);
+ Constant *V[] = {
+ UndefValue::get(LHS->getType()), ConstantInt::getFalse(*Context)
+ };
+ Constant *Struct = ConstantStruct::get(*Context, V, 2, false);
+ return InsertValueInst::Create(Struct, Add, 0);
+ }
+ }
+ }
+ // FALL THROUGH uadd into sadd
+ case Intrinsic::sadd_with_overflow:
+ // Canonicalize constants into the RHS.
+ if (isa<Constant>(II->getOperand(1)) &&
+ !isa<Constant>(II->getOperand(2))) {
+ Value *LHS = II->getOperand(1);
+ II->setOperand(1, II->getOperand(2));
+ II->setOperand(2, LHS);
+ return II;
+ }
+
+ // X + undef -> undef
+ if (isa<UndefValue>(II->getOperand(2)))
+ return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(II->getOperand(2))) {
+ // X + 0 -> {X, false}
+ if (RHS->isZero()) {
+ Constant *V[] = {
+ UndefValue::get(II->getOperand(0)->getType()),
+ ConstantInt::getFalse(*Context)
+ };
+ Constant *Struct = ConstantStruct::get(*Context, V, 2, false);
+ return InsertValueInst::Create(Struct, II->getOperand(1), 0);
+ }
+ }
+ break;
+ case Intrinsic::usub_with_overflow:
+ case Intrinsic::ssub_with_overflow:
+ // undef - X -> undef
+ // X - undef -> undef
+ if (isa<UndefValue>(II->getOperand(1)) ||
+ isa<UndefValue>(II->getOperand(2)))
+ return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(II->getOperand(2))) {
+ // X - 0 -> {X, false}
+ if (RHS->isZero()) {
+ Constant *V[] = {
+ UndefValue::get(II->getOperand(1)->getType()),
+ ConstantInt::getFalse(*Context)
+ };
+ Constant *Struct = ConstantStruct::get(*Context, V, 2, false);
+ return InsertValueInst::Create(Struct, II->getOperand(1), 0);
+ }
+ }
+ break;
+ case Intrinsic::umul_with_overflow:
+ case Intrinsic::smul_with_overflow:
+ // Canonicalize constants into the RHS.
+ if (isa<Constant>(II->getOperand(1)) &&
+ !isa<Constant>(II->getOperand(2))) {
+ Value *LHS = II->getOperand(1);
+ II->setOperand(1, II->getOperand(2));
+ II->setOperand(2, LHS);
+ return II;
+ }
+
+ // X * undef -> undef
+ if (isa<UndefValue>(II->getOperand(2)))
+ return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
+
+ if (ConstantInt *RHSI = dyn_cast<ConstantInt>(II->getOperand(2))) {
+ // X*0 -> {0, false}
+ if (RHSI->isZero())
+ return ReplaceInstUsesWith(CI, Constant::getNullValue(II->getType()));
+
+ // X * 1 -> {X, false}
+ if (RHSI->equalsInt(1)) {
+ Constant *V[] = {
+ UndefValue::get(II->getOperand(1)->getType()),
+ ConstantInt::getFalse(*Context)
+ };
+ Constant *Struct = ConstantStruct::get(*Context, V, 2, false);
+ return InsertValueInst::Create(Struct, II->getOperand(1), 0);
+ }
+ }
+ break;
+ case Intrinsic::ppc_altivec_lvx:
+ case Intrinsic::ppc_altivec_lvxl:
+ case Intrinsic::x86_sse_loadu_ps:
+ case Intrinsic::x86_sse2_loadu_pd:
+ case Intrinsic::x86_sse2_loadu_dq:
+ // Turn PPC lvx -> load if the pointer is known aligned.
+ // Turn X86 loadups -> load if the pointer is known aligned.
+ if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
+ Value *Ptr = Builder->CreateBitCast(II->getOperand(1),
+ PointerType::getUnqual(II->getType()));
+ return new LoadInst(Ptr);
+ }
+ break;
+ case Intrinsic::ppc_altivec_stvx:
+ case Intrinsic::ppc_altivec_stvxl:
+ // Turn stvx -> store if the pointer is known aligned.
+ if (GetOrEnforceKnownAlignment(II->getOperand(2), 16) >= 16) {
+ const Type *OpPtrTy =
+ PointerType::getUnqual(II->getOperand(1)->getType());
+ Value *Ptr = Builder->CreateBitCast(II->getOperand(2), OpPtrTy);
+ return new StoreInst(II->getOperand(1), Ptr);
+ }
+ break;
+ case Intrinsic::x86_sse_storeu_ps:
+ case Intrinsic::x86_sse2_storeu_pd:
+ case Intrinsic::x86_sse2_storeu_dq:
+ // Turn X86 storeu -> store if the pointer is known aligned.
+ if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
+ const Type *OpPtrTy =
+ PointerType::getUnqual(II->getOperand(2)->getType());
+ Value *Ptr = Builder->CreateBitCast(II->getOperand(1), OpPtrTy);
+ return new StoreInst(II->getOperand(2), Ptr);
+ }
+ break;
+
+ case Intrinsic::x86_sse_cvttss2si: {
+ // These intrinsics only demands the 0th element of its input vector. If
+ // we can simplify the input based on that, do so now.
+ unsigned VWidth =
+ cast<VectorType>(II->getOperand(1)->getType())->getNumElements();
+ APInt DemandedElts(VWidth, 1);
+ APInt UndefElts(VWidth, 0);
+ if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
+ UndefElts)) {
+ II->setOperand(1, V);
+ return II;
+ }
+ break;
+ }
+
+ case Intrinsic::ppc_altivec_vperm:
+ // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
+ if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) {
+ assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
+
+ // Check that all of the elements are integer constants or undefs.
+ bool AllEltsOk = true;
+ for (unsigned i = 0; i != 16; ++i) {
+ if (!isa<ConstantInt>(Mask->getOperand(i)) &&
+ !isa<UndefValue>(Mask->getOperand(i))) {
+ AllEltsOk = false;
+ break;
+ }
+ }
+
+ if (AllEltsOk) {
+ // Cast the input vectors to byte vectors.
+ Value *Op0 = Builder->CreateBitCast(II->getOperand(1), Mask->getType());
+ Value *Op1 = Builder->CreateBitCast(II->getOperand(2), Mask->getType());
+ Value *Result = UndefValue::get(Op0->getType());
+
+ // Only extract each element once.
+ Value *ExtractedElts[32];
+ memset(ExtractedElts, 0, sizeof(ExtractedElts));
+
+ for (unsigned i = 0; i != 16; ++i) {
+ if (isa<UndefValue>(Mask->getOperand(i)))
+ continue;
+ unsigned Idx=cast<ConstantInt>(Mask->getOperand(i))->getZExtValue();
+ Idx &= 31; // Match the hardware behavior.
+
+ if (ExtractedElts[Idx] == 0) {
+ ExtractedElts[Idx] =
+ Builder->CreateExtractElement(Idx < 16 ? Op0 : Op1,
+ ConstantInt::get(Type::getInt32Ty(*Context), Idx&15, false),
+ "tmp");
+ }
+
+ // Insert this value into the result vector.
+ Result = Builder->CreateInsertElement(Result, ExtractedElts[Idx],
+ ConstantInt::get(Type::getInt32Ty(*Context), i, false),
+ "tmp");
+ }
+ return CastInst::Create(Instruction::BitCast, Result, CI.getType());
+ }
+ }
+ break;
+
+ case Intrinsic::stackrestore: {
+ // If the save is right next to the restore, remove the restore. This can
+ // happen when variable allocas are DCE'd.
+ if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
+ if (SS->getIntrinsicID() == Intrinsic::stacksave) {
+ BasicBlock::iterator BI = SS;
+ if (&*++BI == II)
+ return EraseInstFromFunction(CI);
+ }
+ }
+
+ // Scan down this block to see if there is another stack restore in the
+ // same block without an intervening call/alloca.
+ BasicBlock::iterator BI = II;
+ TerminatorInst *TI = II->getParent()->getTerminator();
+ bool CannotRemove = false;
+ for (++BI; &*BI != TI; ++BI) {
+ if (isa<AllocaInst>(BI) || isMalloc(BI)) {
+ CannotRemove = true;
+ break;
+ }
+ if (CallInst *BCI = dyn_cast<CallInst>(BI)) {
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BCI)) {
+ // If there is a stackrestore below this one, remove this one.
+ if (II->getIntrinsicID() == Intrinsic::stackrestore)
+ return EraseInstFromFunction(CI);
+ // Otherwise, ignore the intrinsic.
+ } else {
+ // If we found a non-intrinsic call, we can't remove the stack
+ // restore.
+ CannotRemove = true;
+ break;
+ }
+ }
+ }
+
+ // If the stack restore is in a return/unwind block and if there are no
+ // allocas or calls between the restore and the return, nuke the restore.
+ if (!CannotRemove && (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)))
+ return EraseInstFromFunction(CI);
+ break;
+ }
+ }
+
+ return visitCallSite(II);
+}
+
+// InvokeInst simplification
+//
+Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
+ return visitCallSite(&II);
+}
+
+/// isSafeToEliminateVarargsCast - If this cast does not affect the value
+/// passed through the varargs area, we can eliminate the use of the cast.
+static bool isSafeToEliminateVarargsCast(const CallSite CS,
+ const CastInst * const CI,
+ const TargetData * const TD,
+ const int ix) {
+ if (!CI->isLosslessCast())
+ return false;
+
+ // The size of ByVal arguments is derived from the type, so we
+ // can't change to a type with a different size. If the size were
+ // passed explicitly we could avoid this check.
+ if (!CS.paramHasAttr(ix, Attribute::ByVal))
+ return true;
+
+ const Type* SrcTy =
+ cast<PointerType>(CI->getOperand(0)->getType())->getElementType();
+ const Type* DstTy = cast<PointerType>(CI->getType())->getElementType();
+ if (!SrcTy->isSized() || !DstTy->isSized())
+ return false;
+ if (!TD || TD->getTypeAllocSize(SrcTy) != TD->getTypeAllocSize(DstTy))
+ return false;
+ return true;
+}
+
+// visitCallSite - Improvements for call and invoke instructions.
+//
+Instruction *InstCombiner::visitCallSite(CallSite CS) {
+ bool Changed = false;
+
+ // If the callee is a constexpr cast of a function, attempt to move the cast
+ // to the arguments of the call/invoke.
+ if (transformConstExprCastCall(CS)) return 0;
+
+ Value *Callee = CS.getCalledValue();
+
+ if (Function *CalleeF = dyn_cast<Function>(Callee))
+ if (CalleeF->getCallingConv() != CS.getCallingConv()) {
+ Instruction *OldCall = CS.getInstruction();
+ // If the call and callee calling conventions don't match, this call must
+ // be unreachable, as the call is undefined.
+ new StoreInst(ConstantInt::getTrue(*Context),
+ UndefValue::get(Type::getInt1PtrTy(*Context)),
+ OldCall);
+ // If OldCall dues not return void then replaceAllUsesWith undef.
+ // This allows ValueHandlers and custom metadata to adjust itself.
+ if (!OldCall->getType()->isVoidTy())
+ OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
+ if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
+ return EraseInstFromFunction(*OldCall);
+ return 0;
+ }
+
+ if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
+ // This instruction is not reachable, just remove it. We insert a store to
+ // undef so that we know that this code is not reachable, despite the fact
+ // that we can't modify the CFG here.
+ new StoreInst(ConstantInt::getTrue(*Context),
+ UndefValue::get(Type::getInt1PtrTy(*Context)),
+ CS.getInstruction());
+
+ // If CS dues not return void then replaceAllUsesWith undef.
+ // This allows ValueHandlers and custom metadata to adjust itself.
+ if (!CS.getInstruction()->getType()->isVoidTy())
+ CS.getInstruction()->
+ replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
+
+ if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
+ // Don't break the CFG, insert a dummy cond branch.
+ BranchInst::Create(II->getNormalDest(), II->getUnwindDest(),
+ ConstantInt::getTrue(*Context), II);
+ }
+ return EraseInstFromFunction(*CS.getInstruction());
+ }
+
+ if (BitCastInst *BC = dyn_cast<BitCastInst>(Callee))
+ if (IntrinsicInst *In = dyn_cast<IntrinsicInst>(BC->getOperand(0)))
+ if (In->getIntrinsicID() == Intrinsic::init_trampoline)
+ return transformCallThroughTrampoline(CS);
+
+ const PointerType *PTy = cast<PointerType>(Callee->getType());
+ const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
+ if (FTy->isVarArg()) {
+ int ix = FTy->getNumParams() + (isa<InvokeInst>(Callee) ? 3 : 1);
+ // See if we can optimize any arguments passed through the varargs area of
+ // the call.
+ for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
+ E = CS.arg_end(); I != E; ++I, ++ix) {
+ CastInst *CI = dyn_cast<CastInst>(*I);
+ if (CI && isSafeToEliminateVarargsCast(CS, CI, TD, ix)) {
+ *I = CI->getOperand(0);
+ Changed = true;
+ }
+ }
+ }
+
+ if (isa<InlineAsm>(Callee) && !CS.doesNotThrow()) {
+ // Inline asm calls cannot throw - mark them 'nounwind'.
+ CS.setDoesNotThrow();
+ Changed = true;
+ }
+
+ return Changed ? CS.getInstruction() : 0;
+}
+
+// transformConstExprCastCall - If the callee is a constexpr cast of a function,
+// attempt to move the cast to the arguments of the call/invoke.
+//
+bool InstCombiner::transformConstExprCastCall(CallSite CS) {
+ if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
+ ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
+ if (CE->getOpcode() != Instruction::BitCast ||
+ !isa<Function>(CE->getOperand(0)))
+ return false;
+ Function *Callee = cast<Function>(CE->getOperand(0));
+ Instruction *Caller = CS.getInstruction();
+ const AttrListPtr &CallerPAL = CS.getAttributes();
+
+ // Okay, this is a cast from a function to a different type. Unless doing so
+ // would cause a type conversion of one of our arguments, change this call to
+ // be a direct call with arguments casted to the appropriate types.
+ //
+ const FunctionType *FT = Callee->getFunctionType();
+ const Type *OldRetTy = Caller->getType();
+ const Type *NewRetTy = FT->getReturnType();
+
+ if (isa<StructType>(NewRetTy))
+ return false; // TODO: Handle multiple return values.
+
+ // Check to see if we are changing the return type...
+ if (OldRetTy != NewRetTy) {
+ if (Callee->isDeclaration() &&
+ // Conversion is ok if changing from one pointer type to another or from
+ // a pointer to an integer of the same size.
+ !((isa<PointerType>(OldRetTy) || !TD ||
+ OldRetTy == TD->getIntPtrType(Caller->getContext())) &&
+ (isa<PointerType>(NewRetTy) || !TD ||
+ NewRetTy == TD->getIntPtrType(Caller->getContext()))))
+ return false; // Cannot transform this return value.
+
+ if (!Caller->use_empty() &&
+ // void -> non-void is handled specially
+ !NewRetTy->isVoidTy() && !CastInst::isCastable(NewRetTy, OldRetTy))
+ return false; // Cannot transform this return value.
+
+ if (!CallerPAL.isEmpty() && !Caller->use_empty()) {
+ Attributes RAttrs = CallerPAL.getRetAttributes();
+ if (RAttrs & Attribute::typeIncompatible(NewRetTy))
+ return false; // Attribute not compatible with transformed value.
+ }
+
+ // If the callsite is an invoke instruction, and the return value is used by
+ // a PHI node in a successor, we cannot change the return type of the call
+ // because there is no place to put the cast instruction (without breaking
+ // the critical edge). Bail out in this case.
+ if (!Caller->use_empty())
+ if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
+ for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
+ UI != E; ++UI)
+ if (PHINode *PN = dyn_cast<PHINode>(*UI))
+ if (PN->getParent() == II->getNormalDest() ||
+ PN->getParent() == II->getUnwindDest())
+ return false;
+ }
+
+ unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
+ unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
+
+ CallSite::arg_iterator AI = CS.arg_begin();
+ for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
+ const Type *ParamTy = FT->getParamType(i);
+ const Type *ActTy = (*AI)->getType();
+
+ if (!CastInst::isCastable(ActTy, ParamTy))
+ return false; // Cannot transform this parameter value.
+
+ if (CallerPAL.getParamAttributes(i + 1)
+ & Attribute::typeIncompatible(ParamTy))
+ return false; // Attribute not compatible with transformed value.
+
+ // Converting from one pointer type to another or between a pointer and an
+ // integer of the same size is safe even if we do not have a body.
+ bool isConvertible = ActTy == ParamTy ||
+ (TD && ((isa<PointerType>(ParamTy) ||
+ ParamTy == TD->getIntPtrType(Caller->getContext())) &&
+ (isa<PointerType>(ActTy) ||
+ ActTy == TD->getIntPtrType(Caller->getContext()))));
+ if (Callee->isDeclaration() && !isConvertible) return false;
+ }
+
+ if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
+ Callee->isDeclaration())
+ return false; // Do not delete arguments unless we have a function body.
+
+ if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
+ !CallerPAL.isEmpty())
+ // In this case we have more arguments than the new function type, but we
+ // won't be dropping them. Check that these extra arguments have attributes
+ // that are compatible with being a vararg call argument.
+ for (unsigned i = CallerPAL.getNumSlots(); i; --i) {
+ if (CallerPAL.getSlot(i - 1).Index <= FT->getNumParams())
+ break;
+ Attributes PAttrs = CallerPAL.getSlot(i - 1).Attrs;
+ if (PAttrs & Attribute::VarArgsIncompatible)
+ return false;
+ }
+
+ // Okay, we decided that this is a safe thing to do: go ahead and start
+ // inserting cast instructions as necessary...
+ std::vector<Value*> Args;
+ Args.reserve(NumActualArgs);
+ SmallVector<AttributeWithIndex, 8> attrVec;
+ attrVec.reserve(NumCommonArgs);
+
+ // Get any return attributes.
+ Attributes RAttrs = CallerPAL.getRetAttributes();
+
+ // If the return value is not being used, the type may not be compatible
+ // with the existing attributes. Wipe out any problematic attributes.
+ RAttrs &= ~Attribute::typeIncompatible(NewRetTy);
+
+ // Add the new return attributes.
+ if (RAttrs)
+ attrVec.push_back(AttributeWithIndex::get(0, RAttrs));
+
+ AI = CS.arg_begin();
+ for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
+ const Type *ParamTy = FT->getParamType(i);
+ if ((*AI)->getType() == ParamTy) {
+ Args.push_back(*AI);
+ } else {
+ Instruction::CastOps opcode = CastInst::getCastOpcode(*AI,
+ false, ParamTy, false);
+ Args.push_back(Builder->CreateCast(opcode, *AI, ParamTy, "tmp"));
+ }
+
+ // Add any parameter attributes.
+ if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
+ attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
+ }
+
+ // If the function takes more arguments than the call was taking, add them
+ // now.
+ for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
+ Args.push_back(Constant::getNullValue(FT->getParamType(i)));
+
+ // If we are removing arguments to the function, emit an obnoxious warning.
+ if (FT->getNumParams() < NumActualArgs) {
+ if (!FT->isVarArg()) {
+ errs() << "WARNING: While resolving call to function '"
+ << Callee->getName() << "' arguments were dropped!\n";
+ } else {
+ // Add all of the arguments in their promoted form to the arg list.
+ for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
+ const Type *PTy = getPromotedType((*AI)->getType());
+ if (PTy != (*AI)->getType()) {
+ // Must promote to pass through va_arg area!
+ Instruction::CastOps opcode =
+ CastInst::getCastOpcode(*AI, false, PTy, false);
+ Args.push_back(Builder->CreateCast(opcode, *AI, PTy, "tmp"));
+ } else {
+ Args.push_back(*AI);
+ }
+
+ // Add any parameter attributes.
+ if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
+ attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
+ }
+ }
+ }
+
+ if (Attributes FnAttrs = CallerPAL.getFnAttributes())
+ attrVec.push_back(AttributeWithIndex::get(~0, FnAttrs));
+
+ if (NewRetTy->isVoidTy())
+ Caller->setName(""); // Void type should not have a name.
+
+ const AttrListPtr &NewCallerPAL = AttrListPtr::get(attrVec.begin(),
+ attrVec.end());
+
+ Instruction *NC;
+ if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
+ NC = InvokeInst::Create(Callee, II->getNormalDest(), II->getUnwindDest(),
+ Args.begin(), Args.end(),
+ Caller->getName(), Caller);
+ cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
+ cast<InvokeInst>(NC)->setAttributes(NewCallerPAL);
+ } else {
+ NC = CallInst::Create(Callee, Args.begin(), Args.end(),
+ Caller->getName(), Caller);
+ CallInst *CI = cast<CallInst>(Caller);
+ if (CI->isTailCall())
+ cast<CallInst>(NC)->setTailCall();
+ cast<CallInst>(NC)->setCallingConv(CI->getCallingConv());
+ cast<CallInst>(NC)->setAttributes(NewCallerPAL);
+ }
+
+ // Insert a cast of the return type as necessary.
+ Value *NV = NC;
+ if (OldRetTy != NV->getType() && !Caller->use_empty()) {
+ if (!NV->getType()->isVoidTy()) {
+ Instruction::CastOps opcode = CastInst::getCastOpcode(NC, false,
+ OldRetTy, false);
+ NV = NC = CastInst::Create(opcode, NC, OldRetTy, "tmp");
+
+ // If this is an invoke instruction, we should insert it after the first
+ // non-phi, instruction in the normal successor block.
+ if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
+ BasicBlock::iterator I = II->getNormalDest()->getFirstNonPHI();
+ InsertNewInstBefore(NC, *I);
+ } else {
+ // Otherwise, it's a call, just insert cast right after the call instr
+ InsertNewInstBefore(NC, *Caller);
+ }
+ Worklist.AddUsersToWorkList(*Caller);
+ } else {
+ NV = UndefValue::get(Caller->getType());
+ }
+ }
+
+
+ if (!Caller->use_empty())
+ Caller->replaceAllUsesWith(NV);
+
+ EraseInstFromFunction(*Caller);
+ return true;
+}
+
+// transformCallThroughTrampoline - Turn a call to a function created by the
+// init_trampoline intrinsic into a direct call to the underlying function.
+//
+Instruction *InstCombiner::transformCallThroughTrampoline(CallSite CS) {
+ Value *Callee = CS.getCalledValue();
+ const PointerType *PTy = cast<PointerType>(Callee->getType());
+ const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
+ const AttrListPtr &Attrs = CS.getAttributes();
+
+ // If the call already has the 'nest' attribute somewhere then give up -
+ // otherwise 'nest' would occur twice after splicing in the chain.
+ if (Attrs.hasAttrSomewhere(Attribute::Nest))
+ return 0;
+
+ IntrinsicInst *Tramp =
+ cast<IntrinsicInst>(cast<BitCastInst>(Callee)->getOperand(0));
+
+ Function *NestF = cast<Function>(Tramp->getOperand(2)->stripPointerCasts());
+ const PointerType *NestFPTy = cast<PointerType>(NestF->getType());
+ const FunctionType *NestFTy = cast<FunctionType>(NestFPTy->getElementType());
+
+ const AttrListPtr &NestAttrs = NestF->getAttributes();
+ if (!NestAttrs.isEmpty()) {
+ unsigned NestIdx = 1;
+ const Type *NestTy = 0;
+ Attributes NestAttr = Attribute::None;
+
+ // Look for a parameter marked with the 'nest' attribute.
+ for (FunctionType::param_iterator I = NestFTy->param_begin(),
+ E = NestFTy->param_end(); I != E; ++NestIdx, ++I)
+ if (NestAttrs.paramHasAttr(NestIdx, Attribute::Nest)) {
+ // Record the parameter type and any other attributes.
+ NestTy = *I;
+ NestAttr = NestAttrs.getParamAttributes(NestIdx);
+ break;
+ }
+
+ if (NestTy) {
+ Instruction *Caller = CS.getInstruction();
+ std::vector<Value*> NewArgs;
+ NewArgs.reserve(unsigned(CS.arg_end()-CS.arg_begin())+1);
+
+ SmallVector<AttributeWithIndex, 8> NewAttrs;
+ NewAttrs.reserve(Attrs.getNumSlots() + 1);
+
+ // Insert the nest argument into the call argument list, which may
+ // mean appending it. Likewise for attributes.
+
+ // Add any result attributes.
+ if (Attributes Attr = Attrs.getRetAttributes())
+ NewAttrs.push_back(AttributeWithIndex::get(0, Attr));
+
+ {
+ unsigned Idx = 1;
+ CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
+ do {
+ if (Idx == NestIdx) {
+ // Add the chain argument and attributes.
+ Value *NestVal = Tramp->getOperand(3);
+ if (NestVal->getType() != NestTy)
+ NestVal = new BitCastInst(NestVal, NestTy, "nest", Caller);
+ NewArgs.push_back(NestVal);
+ NewAttrs.push_back(AttributeWithIndex::get(NestIdx, NestAttr));
+ }
+
+ if (I == E)
+ break;
+
+ // Add the original argument and attributes.
+ NewArgs.push_back(*I);
+ if (Attributes Attr = Attrs.getParamAttributes(Idx))
+ NewAttrs.push_back
+ (AttributeWithIndex::get(Idx + (Idx >= NestIdx), Attr));
+
+ ++Idx, ++I;
+ } while (1);
+ }
+
+ // Add any function attributes.
+ if (Attributes Attr = Attrs.getFnAttributes())
+ NewAttrs.push_back(AttributeWithIndex::get(~0, Attr));
+
+ // The trampoline may have been bitcast to a bogus type (FTy).
+ // Handle this by synthesizing a new function type, equal to FTy
+ // with the chain parameter inserted.
+
+ std::vector<const Type*> NewTypes;
+ NewTypes.reserve(FTy->getNumParams()+1);
+
+ // Insert the chain's type into the list of parameter types, which may
+ // mean appending it.
+ {
+ unsigned Idx = 1;
+ FunctionType::param_iterator I = FTy->param_begin(),
+ E = FTy->param_end();
+
+ do {
+ if (Idx == NestIdx)
+ // Add the chain's type.
+ NewTypes.push_back(NestTy);
+
+ if (I == E)
+ break;
+
+ // Add the original type.
+ NewTypes.push_back(*I);
+
+ ++Idx, ++I;
+ } while (1);
+ }
+
+ // Replace the trampoline call with a direct call. Let the generic
+ // code sort out any function type mismatches.
+ FunctionType *NewFTy = FunctionType::get(FTy->getReturnType(), NewTypes,
+ FTy->isVarArg());
+ Constant *NewCallee =
+ NestF->getType() == PointerType::getUnqual(NewFTy) ?
+ NestF : ConstantExpr::getBitCast(NestF,
+ PointerType::getUnqual(NewFTy));
+ const AttrListPtr &NewPAL = AttrListPtr::get(NewAttrs.begin(),
+ NewAttrs.end());
+
+ Instruction *NewCaller;
+ if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
+ NewCaller = InvokeInst::Create(NewCallee,
+ II->getNormalDest(), II->getUnwindDest(),
+ NewArgs.begin(), NewArgs.end(),
+ Caller->getName(), Caller);
+ cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
+ cast<InvokeInst>(NewCaller)->setAttributes(NewPAL);
+ } else {
+ NewCaller = CallInst::Create(NewCallee, NewArgs.begin(), NewArgs.end(),
+ Caller->getName(), Caller);
+ if (cast<CallInst>(Caller)->isTailCall())
+ cast<CallInst>(NewCaller)->setTailCall();
+ cast<CallInst>(NewCaller)->
+ setCallingConv(cast<CallInst>(Caller)->getCallingConv());
+ cast<CallInst>(NewCaller)->setAttributes(NewPAL);
+ }
+ if (!Caller->getType()->isVoidTy())
+ Caller->replaceAllUsesWith(NewCaller);
+ Caller->eraseFromParent();
+ Worklist.Remove(Caller);
+ return 0;
+ }
+ }
+
+ // Replace the trampoline call with a direct call. Since there is no 'nest'
+ // parameter, there is no need to adjust the argument list. Let the generic
+ // code sort out any function type mismatches.
+ Constant *NewCallee =
+ NestF->getType() == PTy ? NestF :
+ ConstantExpr::getBitCast(NestF, PTy);
+ CS.setCalledFunction(NewCallee);
+ return CS.getInstruction();
+}
+
+/// FoldPHIArgBinOpIntoPHI - If we have something like phi [add (a,b), add(a,c)]
+/// and if a/b/c and the add's all have a single use, turn this into a phi
+/// and a single binop.
+Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
+ Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
+ assert(isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst));
+ unsigned Opc = FirstInst->getOpcode();
+ Value *LHSVal = FirstInst->getOperand(0);
+ Value *RHSVal = FirstInst->getOperand(1);
+
+ const Type *LHSType = LHSVal->getType();
+ const Type *RHSType = RHSVal->getType();
+
+ // Scan to see if all operands are the same opcode, and all have one use.
+ for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
+ Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
+ if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
+ // Verify type of the LHS matches so we don't fold cmp's of different
+ // types or GEP's with different index types.
+ I->getOperand(0)->getType() != LHSType ||
+ I->getOperand(1)->getType() != RHSType)
+ return 0;
+
+ // If they are CmpInst instructions, check their predicates
+ if (Opc == Instruction::ICmp || Opc == Instruction::FCmp)
+ if (cast<CmpInst>(I)->getPredicate() !=
+ cast<CmpInst>(FirstInst)->getPredicate())
+ return 0;
+
+ // Keep track of which operand needs a phi node.
+ if (I->getOperand(0) != LHSVal) LHSVal = 0;
+ if (I->getOperand(1) != RHSVal) RHSVal = 0;
+ }
+
+ // If both LHS and RHS would need a PHI, don't do this transformation,
+ // because it would increase the number of PHIs entering the block,
+ // which leads to higher register pressure. This is especially
+ // bad when the PHIs are in the header of a loop.
+ if (!LHSVal && !RHSVal)
+ return 0;
+
+ // Otherwise, this is safe to transform!
+
+ Value *InLHS = FirstInst->getOperand(0);
+ Value *InRHS = FirstInst->getOperand(1);
+ PHINode *NewLHS = 0, *NewRHS = 0;
+ if (LHSVal == 0) {
+ NewLHS = PHINode::Create(LHSType,
+ FirstInst->getOperand(0)->getName() + ".pn");
+ NewLHS->reserveOperandSpace(PN.getNumOperands()/2);
+ NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0));
+ InsertNewInstBefore(NewLHS, PN);
+ LHSVal = NewLHS;
+ }
+
+ if (RHSVal == 0) {
+ NewRHS = PHINode::Create(RHSType,
+ FirstInst->getOperand(1)->getName() + ".pn");
+ NewRHS->reserveOperandSpace(PN.getNumOperands()/2);
+ NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0));
+ InsertNewInstBefore(NewRHS, PN);
+ RHSVal = NewRHS;
+ }
+
+ // Add all operands to the new PHIs.
+ if (NewLHS || NewRHS) {
+ for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+ Instruction *InInst = cast<Instruction>(PN.getIncomingValue(i));
+ if (NewLHS) {
+ Value *NewInLHS = InInst->getOperand(0);
+ NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i));
+ }
+ if (NewRHS) {
+ Value *NewInRHS = InInst->getOperand(1);
+ NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i));
+ }
+ }
+ }
+
+ if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
+ return BinaryOperator::Create(BinOp->getOpcode(), LHSVal, RHSVal);
+ CmpInst *CIOp = cast<CmpInst>(FirstInst);
+ return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
+ LHSVal, RHSVal);
+}
+
+Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
+ GetElementPtrInst *FirstInst =cast<GetElementPtrInst>(PN.getIncomingValue(0));
+
+ SmallVector<Value*, 16> FixedOperands(FirstInst->op_begin(),
+ FirstInst->op_end());
+ // This is true if all GEP bases are allocas and if all indices into them are
+ // constants.
+ bool AllBasePointersAreAllocas = true;
+
+ // We don't want to replace this phi if the replacement would require
+ // more than one phi, which leads to higher register pressure. This is
+ // especially bad when the PHIs are in the header of a loop.
+ bool NeededPhi = false;
+
+ // Scan to see if all operands are the same opcode, and all have one use.
+ for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
+ GetElementPtrInst *GEP= dyn_cast<GetElementPtrInst>(PN.getIncomingValue(i));
+ if (!GEP || !GEP->hasOneUse() || GEP->getType() != FirstInst->getType() ||
+ GEP->getNumOperands() != FirstInst->getNumOperands())
+ return 0;
+
+ // Keep track of whether or not all GEPs are of alloca pointers.
+ if (AllBasePointersAreAllocas &&
+ (!isa<AllocaInst>(GEP->getOperand(0)) ||
+ !GEP->hasAllConstantIndices()))
+ AllBasePointersAreAllocas = false;
+
+ // Compare the operand lists.
+ for (unsigned op = 0, e = FirstInst->getNumOperands(); op != e; ++op) {
+ if (FirstInst->getOperand(op) == GEP->getOperand(op))
+ continue;
+
+ // Don't merge two GEPs when two operands differ (introducing phi nodes)
+ // if one of the PHIs has a constant for the index. The index may be
+ // substantially cheaper to compute for the constants, so making it a
+ // variable index could pessimize the path. This also handles the case
+ // for struct indices, which must always be constant.
+ if (isa<ConstantInt>(FirstInst->getOperand(op)) ||
+ isa<ConstantInt>(GEP->getOperand(op)))
+ return 0;
+
+ if (FirstInst->getOperand(op)->getType() !=GEP->getOperand(op)->getType())
+ return 0;
+
+ // If we already needed a PHI for an earlier operand, and another operand
+ // also requires a PHI, we'd be introducing more PHIs than we're
+ // eliminating, which increases register pressure on entry to the PHI's
+ // block.
+ if (NeededPhi)
+ return 0;
+
+ FixedOperands[op] = 0; // Needs a PHI.
+ NeededPhi = true;
+ }
+ }
+
+ // If all of the base pointers of the PHI'd GEPs are from allocas, don't
+ // bother doing this transformation. At best, this will just save a bit of
+ // offset calculation, but all the predecessors will have to materialize the
+ // stack address into a register anyway. We'd actually rather *clone* the
+ // load up into the predecessors so that we have a load of a gep of an alloca,
+ // which can usually all be folded into the load.
+ if (AllBasePointersAreAllocas)
+ return 0;
+
+ // Otherwise, this is safe to transform. Insert PHI nodes for each operand
+ // that is variable.
+ SmallVector<PHINode*, 16> OperandPhis(FixedOperands.size());
+
+ bool HasAnyPHIs = false;
+ for (unsigned i = 0, e = FixedOperands.size(); i != e; ++i) {
+ if (FixedOperands[i]) continue; // operand doesn't need a phi.
+ Value *FirstOp = FirstInst->getOperand(i);
+ PHINode *NewPN = PHINode::Create(FirstOp->getType(),
+ FirstOp->getName()+".pn");
+ InsertNewInstBefore(NewPN, PN);
+
+ NewPN->reserveOperandSpace(e);
+ NewPN->addIncoming(FirstOp, PN.getIncomingBlock(0));
+ OperandPhis[i] = NewPN;
+ FixedOperands[i] = NewPN;
+ HasAnyPHIs = true;
+ }
+
+
+ // Add all operands to the new PHIs.
+ if (HasAnyPHIs) {
+ for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+ GetElementPtrInst *InGEP =cast<GetElementPtrInst>(PN.getIncomingValue(i));
+ BasicBlock *InBB = PN.getIncomingBlock(i);
+
+ for (unsigned op = 0, e = OperandPhis.size(); op != e; ++op)
+ if (PHINode *OpPhi = OperandPhis[op])
+ OpPhi->addIncoming(InGEP->getOperand(op), InBB);
+ }
+ }
+
+ Value *Base = FixedOperands[0];
+ return cast<GEPOperator>(FirstInst)->isInBounds() ?
+ GetElementPtrInst::CreateInBounds(Base, FixedOperands.begin()+1,
+ FixedOperands.end()) :
+ GetElementPtrInst::Create(Base, FixedOperands.begin()+1,
+ FixedOperands.end());
+}
+
+
+/// isSafeAndProfitableToSinkLoad - Return true if we know that it is safe to
+/// sink the load out of the block that defines it. This means that it must be
+/// obvious the value of the load is not changed from the point of the load to
+/// the end of the block it is in.
+///
+/// Finally, it is safe, but not profitable, to sink a load targetting a
+/// non-address-taken alloca. Doing so will cause us to not promote the alloca
+/// to a register.
+static bool isSafeAndProfitableToSinkLoad(LoadInst *L) {
+ BasicBlock::iterator BBI = L, E = L->getParent()->end();
+
+ for (++BBI; BBI != E; ++BBI)
+ if (BBI->mayWriteToMemory())
+ return false;
+
+ // Check for non-address taken alloca. If not address-taken already, it isn't
+ // profitable to do this xform.
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) {
+ bool isAddressTaken = false;
+ for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
+ UI != E; ++UI) {
+ if (isa<LoadInst>(UI)) continue;
+ if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
+ // If storing TO the alloca, then the address isn't taken.
+ if (SI->getOperand(1) == AI) continue;
+ }
+ isAddressTaken = true;
+ break;
+ }
+
+ if (!isAddressTaken && AI->isStaticAlloca())
+ return false;
+ }
+
+ // If this load is a load from a GEP with a constant offset from an alloca,
+ // then we don't want to sink it. In its present form, it will be
+ // load [constant stack offset]. Sinking it will cause us to have to
+ // materialize the stack addresses in each predecessor in a register only to
+ // do a shared load from register in the successor.
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(L->getOperand(0)))
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(GEP->getOperand(0)))
+ if (AI->isStaticAlloca() && GEP->hasAllConstantIndices())
+ return false;
+
+ return true;
+}
+
+Instruction *InstCombiner::FoldPHIArgLoadIntoPHI(PHINode &PN) {
+ LoadInst *FirstLI = cast<LoadInst>(PN.getIncomingValue(0));
+
+ // When processing loads, we need to propagate two bits of information to the
+ // sunk load: whether it is volatile, and what its alignment is. We currently
+ // don't sink loads when some have their alignment specified and some don't.
+ // visitLoadInst will propagate an alignment onto the load when TD is around,
+ // and if TD isn't around, we can't handle the mixed case.
+ bool isVolatile = FirstLI->isVolatile();
+ unsigned LoadAlignment = FirstLI->getAlignment();
+
+ // We can't sink the load if the loaded value could be modified between the
+ // load and the PHI.
+ if (FirstLI->getParent() != PN.getIncomingBlock(0) ||
+ !isSafeAndProfitableToSinkLoad(FirstLI))
+ return 0;
+
+ // If the PHI is of volatile loads and the load block has multiple
+ // successors, sinking it would remove a load of the volatile value from
+ // the path through the other successor.
+ if (isVolatile &&
+ FirstLI->getParent()->getTerminator()->getNumSuccessors() != 1)
+ return 0;
+
+ // Check to see if all arguments are the same operation.
+ for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+ LoadInst *LI = dyn_cast<LoadInst>(PN.getIncomingValue(i));
+ if (!LI || !LI->hasOneUse())
+ return 0;
+
+ // We can't sink the load if the loaded value could be modified between
+ // the load and the PHI.
+ if (LI->isVolatile() != isVolatile ||
+ LI->getParent() != PN.getIncomingBlock(i) ||
+ !isSafeAndProfitableToSinkLoad(LI))
+ return 0;
+
+ // If some of the loads have an alignment specified but not all of them,
+ // we can't do the transformation.
+ if ((LoadAlignment != 0) != (LI->getAlignment() != 0))
+ return 0;
+
+ LoadAlignment = std::min(LoadAlignment, LI->getAlignment());
+
+ // If the PHI is of volatile loads and the load block has multiple
+ // successors, sinking it would remove a load of the volatile value from
+ // the path through the other successor.
+ if (isVolatile &&
+ LI->getParent()->getTerminator()->getNumSuccessors() != 1)
+ return 0;
+ }
+
+ // Okay, they are all the same operation. Create a new PHI node of the
+ // correct type, and PHI together all of the LHS's of the instructions.
+ PHINode *NewPN = PHINode::Create(FirstLI->getOperand(0)->getType(),
+ PN.getName()+".in");
+ NewPN->reserveOperandSpace(PN.getNumOperands()/2);
+
+ Value *InVal = FirstLI->getOperand(0);
+ NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
+
+ // Add all operands to the new PHI.
+ for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+ Value *NewInVal = cast<LoadInst>(PN.getIncomingValue(i))->getOperand(0);
+ if (NewInVal != InVal)
+ InVal = 0;
+ NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
+ }
+
+ Value *PhiVal;
+ if (InVal) {
+ // The new PHI unions all of the same values together. This is really
+ // common, so we handle it intelligently here for compile-time speed.
+ PhiVal = InVal;
+ delete NewPN;
+ } else {
+ InsertNewInstBefore(NewPN, PN);
+ PhiVal = NewPN;
+ }
+
+ // If this was a volatile load that we are merging, make sure to loop through
+ // and mark all the input loads as non-volatile. If we don't do this, we will
+ // insert a new volatile load and the old ones will not be deletable.
+ if (isVolatile)
+ for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
+ cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false);
+
+ return new LoadInst(PhiVal, "", isVolatile, LoadAlignment);
+}
+
+
+
+/// FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
+/// operator and they all are only used by the PHI, PHI together their
+/// inputs, and do the operation once, to the result of the PHI.
+Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
+ Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
+
+ if (isa<GetElementPtrInst>(FirstInst))
+ return FoldPHIArgGEPIntoPHI(PN);
+ if (isa<LoadInst>(FirstInst))
+ return FoldPHIArgLoadIntoPHI(PN);
+
+ // Scan the instruction, looking for input operations that can be folded away.
+ // If all input operands to the phi are the same instruction (e.g. a cast from
+ // the same type or "+42") we can pull the operation through the PHI, reducing
+ // code size and simplifying code.
+ Constant *ConstantOp = 0;
+ const Type *CastSrcTy = 0;
+
+ if (isa<CastInst>(FirstInst)) {
+ CastSrcTy = FirstInst->getOperand(0)->getType();
+
+ // Be careful about transforming integer PHIs. We don't want to pessimize
+ // the code by turning an i32 into an i1293.
+ if (isa<IntegerType>(PN.getType()) && isa<IntegerType>(CastSrcTy)) {
+ if (!ShouldChangeType(PN.getType(), CastSrcTy, TD))
+ return 0;
+ }
+ } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
+ // Can fold binop, compare or shift here if the RHS is a constant,
+ // otherwise call FoldPHIArgBinOpIntoPHI.
+ ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
+ if (ConstantOp == 0)
+ return FoldPHIArgBinOpIntoPHI(PN);
+ } else {
+ return 0; // Cannot fold this operation.
+ }
+
+ // Check to see if all arguments are the same operation.
+ for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+ Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
+ if (I == 0 || !I->hasOneUse() || !I->isSameOperationAs(FirstInst))
+ return 0;
+ if (CastSrcTy) {
+ if (I->getOperand(0)->getType() != CastSrcTy)
+ return 0; // Cast operation must match.
+ } else if (I->getOperand(1) != ConstantOp) {
+ return 0;
+ }
+ }
+
+ // Okay, they are all the same operation. Create a new PHI node of the
+ // correct type, and PHI together all of the LHS's of the instructions.
+ PHINode *NewPN = PHINode::Create(FirstInst->getOperand(0)->getType(),
+ PN.getName()+".in");
+ NewPN->reserveOperandSpace(PN.getNumOperands()/2);
+
+ Value *InVal = FirstInst->getOperand(0);
+ NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
+
+ // Add all operands to the new PHI.
+ for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+ Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
+ if (NewInVal != InVal)
+ InVal = 0;
+ NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
+ }
+
+ Value *PhiVal;
+ if (InVal) {
+ // The new PHI unions all of the same values together. This is really
+ // common, so we handle it intelligently here for compile-time speed.
+ PhiVal = InVal;
+ delete NewPN;
+ } else {
+ InsertNewInstBefore(NewPN, PN);
+ PhiVal = NewPN;
+ }
+
+ // Insert and return the new operation.
+ if (CastInst *FirstCI = dyn_cast<CastInst>(FirstInst))
+ return CastInst::Create(FirstCI->getOpcode(), PhiVal, PN.getType());
+
+ if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
+ return BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp);
+
+ CmpInst *CIOp = cast<CmpInst>(FirstInst);
+ return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
+ PhiVal, ConstantOp);
+}
+
+/// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
+/// that is dead.
+static bool DeadPHICycle(PHINode *PN,
+ SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) {
+ if (PN->use_empty()) return true;
+ if (!PN->hasOneUse()) return false;
+
+ // Remember this node, and if we find the cycle, return.
+ if (!PotentiallyDeadPHIs.insert(PN))
+ return true;
+
+ // Don't scan crazily complex things.
+ if (PotentiallyDeadPHIs.size() == 16)
+ return false;
+
+ if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
+ return DeadPHICycle(PU, PotentiallyDeadPHIs);
+
+ return false;
+}
+
+/// PHIsEqualValue - Return true if this phi node is always equal to
+/// NonPhiInVal. This happens with mutually cyclic phi nodes like:
+/// z = some value; x = phi (y, z); y = phi (x, z)
+static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal,
+ SmallPtrSet<PHINode*, 16> &ValueEqualPHIs) {
+ // See if we already saw this PHI node.
+ if (!ValueEqualPHIs.insert(PN))
+ return true;
+
+ // Don't scan crazily complex things.
+ if (ValueEqualPHIs.size() == 16)
+ return false;
+
+ // Scan the operands to see if they are either phi nodes or are equal to
+ // the value.
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ Value *Op = PN->getIncomingValue(i);
+ if (PHINode *OpPN = dyn_cast<PHINode>(Op)) {
+ if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs))
+ return false;
+ } else if (Op != NonPhiInVal)
+ return false;
+ }
+
+ return true;
+}
+
+
+namespace {
+struct PHIUsageRecord {
+ unsigned PHIId; // The ID # of the PHI (something determinstic to sort on)
+ unsigned Shift; // The amount shifted.
+ Instruction *Inst; // The trunc instruction.
+
+ PHIUsageRecord(unsigned pn, unsigned Sh, Instruction *User)
+ : PHIId(pn), Shift(Sh), Inst(User) {}
+
+ bool operator<(const PHIUsageRecord &RHS) const {
+ if (PHIId < RHS.PHIId) return true;
+ if (PHIId > RHS.PHIId) return false;
+ if (Shift < RHS.Shift) return true;
+ if (Shift > RHS.Shift) return false;
+ return Inst->getType()->getPrimitiveSizeInBits() <
+ RHS.Inst->getType()->getPrimitiveSizeInBits();
+ }
+};
+
+struct LoweredPHIRecord {
+ PHINode *PN; // The PHI that was lowered.
+ unsigned Shift; // The amount shifted.
+ unsigned Width; // The width extracted.
+
+ LoweredPHIRecord(PHINode *pn, unsigned Sh, const Type *Ty)
+ : PN(pn), Shift(Sh), Width(Ty->getPrimitiveSizeInBits()) {}
+
+ // Ctor form used by DenseMap.
+ LoweredPHIRecord(PHINode *pn, unsigned Sh)
+ : PN(pn), Shift(Sh), Width(0) {}
+};
+}
+
+namespace llvm {
+ template<>
+ struct DenseMapInfo<LoweredPHIRecord> {
+ static inline LoweredPHIRecord getEmptyKey() {
+ return LoweredPHIRecord(0, 0);
+ }
+ static inline LoweredPHIRecord getTombstoneKey() {
+ return LoweredPHIRecord(0, 1);
+ }
+ static unsigned getHashValue(const LoweredPHIRecord &Val) {
+ return DenseMapInfo<PHINode*>::getHashValue(Val.PN) ^ (Val.Shift>>3) ^
+ (Val.Width>>3);
+ }
+ static bool isEqual(const LoweredPHIRecord &LHS,
+ const LoweredPHIRecord &RHS) {
+ return LHS.PN == RHS.PN && LHS.Shift == RHS.Shift &&
+ LHS.Width == RHS.Width;
+ }
+ };
+ template <>
+ struct isPodLike<LoweredPHIRecord> { static const bool value = true; };
+}
+
+
+/// SliceUpIllegalIntegerPHI - This is an integer PHI and we know that it has an
+/// illegal type: see if it is only used by trunc or trunc(lshr) operations. If
+/// so, we split the PHI into the various pieces being extracted. This sort of
+/// thing is introduced when SROA promotes an aggregate to large integer values.
+///
+/// TODO: The user of the trunc may be an bitcast to float/double/vector or an
+/// inttoptr. We should produce new PHIs in the right type.
+///
+Instruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &FirstPhi) {
+ // PHIUsers - Keep track of all of the truncated values extracted from a set
+ // of PHIs, along with their offset. These are the things we want to rewrite.
+ SmallVector<PHIUsageRecord, 16> PHIUsers;
+
+ // PHIs are often mutually cyclic, so we keep track of a whole set of PHI
+ // nodes which are extracted from. PHIsToSlice is a set we use to avoid
+ // revisiting PHIs, PHIsInspected is a ordered list of PHIs that we need to
+ // check the uses of (to ensure they are all extracts).
+ SmallVector<PHINode*, 8> PHIsToSlice;
+ SmallPtrSet<PHINode*, 8> PHIsInspected;
+
+ PHIsToSlice.push_back(&FirstPhi);
+ PHIsInspected.insert(&FirstPhi);
+
+ for (unsigned PHIId = 0; PHIId != PHIsToSlice.size(); ++PHIId) {
+ PHINode *PN = PHIsToSlice[PHIId];
+
+ // Scan the input list of the PHI. If any input is an invoke, and if the
+ // input is defined in the predecessor, then we won't be split the critical
+ // edge which is required to insert a truncate. Because of this, we have to
+ // bail out.
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ InvokeInst *II = dyn_cast<InvokeInst>(PN->getIncomingValue(i));
+ if (II == 0) continue;
+ if (II->getParent() != PN->getIncomingBlock(i))
+ continue;
+
+ // If we have a phi, and if it's directly in the predecessor, then we have
+ // a critical edge where we need to put the truncate. Since we can't
+ // split the edge in instcombine, we have to bail out.
+ return 0;
+ }
+
+
+ for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end();
+ UI != E; ++UI) {
+ Instruction *User = cast<Instruction>(*UI);
+
+ // If the user is a PHI, inspect its uses recursively.
+ if (PHINode *UserPN = dyn_cast<PHINode>(User)) {
+ if (PHIsInspected.insert(UserPN))
+ PHIsToSlice.push_back(UserPN);
+ continue;
+ }
+
+ // Truncates are always ok.
+ if (isa<TruncInst>(User)) {
+ PHIUsers.push_back(PHIUsageRecord(PHIId, 0, User));
+ continue;
+ }
+
+ // Otherwise it must be a lshr which can only be used by one trunc.
+ if (User->getOpcode() != Instruction::LShr ||
+ !User->hasOneUse() || !isa<TruncInst>(User->use_back()) ||
+ !isa<ConstantInt>(User->getOperand(1)))
+ return 0;
+
+ unsigned Shift = cast<ConstantInt>(User->getOperand(1))->getZExtValue();
+ PHIUsers.push_back(PHIUsageRecord(PHIId, Shift, User->use_back()));
+ }
+ }
+
+ // If we have no users, they must be all self uses, just nuke the PHI.
+ if (PHIUsers.empty())
+ return ReplaceInstUsesWith(FirstPhi, UndefValue::get(FirstPhi.getType()));
+
+ // If this phi node is transformable, create new PHIs for all the pieces
+ // extracted out of it. First, sort the users by their offset and size.
+ array_pod_sort(PHIUsers.begin(), PHIUsers.end());
+
+ DEBUG(errs() << "SLICING UP PHI: " << FirstPhi << '\n';
+ for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i)
+ errs() << "AND USER PHI #" << i << ": " << *PHIsToSlice[i] <<'\n';
+ );
+
+ // PredValues - This is a temporary used when rewriting PHI nodes. It is
+ // hoisted out here to avoid construction/destruction thrashing.
+ DenseMap<BasicBlock*, Value*> PredValues;
+
+ // ExtractedVals - Each new PHI we introduce is saved here so we don't
+ // introduce redundant PHIs.
+ DenseMap<LoweredPHIRecord, PHINode*> ExtractedVals;
+
+ for (unsigned UserI = 0, UserE = PHIUsers.size(); UserI != UserE; ++UserI) {
+ unsigned PHIId = PHIUsers[UserI].PHIId;
+ PHINode *PN = PHIsToSlice[PHIId];
+ unsigned Offset = PHIUsers[UserI].Shift;
+ const Type *Ty = PHIUsers[UserI].Inst->getType();
+
+ PHINode *EltPHI;
+
+ // If we've already lowered a user like this, reuse the previously lowered
+ // value.
+ if ((EltPHI = ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)]) == 0) {
+
+ // Otherwise, Create the new PHI node for this user.
+ EltPHI = PHINode::Create(Ty, PN->getName()+".off"+Twine(Offset), PN);
+ assert(EltPHI->getType() != PN->getType() &&
+ "Truncate didn't shrink phi?");
+
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ BasicBlock *Pred = PN->getIncomingBlock(i);
+ Value *&PredVal = PredValues[Pred];
+
+ // If we already have a value for this predecessor, reuse it.
+ if (PredVal) {
+ EltPHI->addIncoming(PredVal, Pred);
+ continue;
+ }
+
+ // Handle the PHI self-reuse case.
+ Value *InVal = PN->getIncomingValue(i);
+ if (InVal == PN) {
+ PredVal = EltPHI;
+ EltPHI->addIncoming(PredVal, Pred);
+ continue;
+ }
+
+ if (PHINode *InPHI = dyn_cast<PHINode>(PN)) {
+ // If the incoming value was a PHI, and if it was one of the PHIs we
+ // already rewrote it, just use the lowered value.
+ if (Value *Res = ExtractedVals[LoweredPHIRecord(InPHI, Offset, Ty)]) {
+ PredVal = Res;
+ EltPHI->addIncoming(PredVal, Pred);
+ continue;
+ }
+ }
+
+ // Otherwise, do an extract in the predecessor.
+ Builder->SetInsertPoint(Pred, Pred->getTerminator());
+ Value *Res = InVal;
+ if (Offset)
+ Res = Builder->CreateLShr(Res, ConstantInt::get(InVal->getType(),
+ Offset), "extract");
+ Res = Builder->CreateTrunc(Res, Ty, "extract.t");
+ PredVal = Res;
+ EltPHI->addIncoming(Res, Pred);
+
+ // If the incoming value was a PHI, and if it was one of the PHIs we are
+ // rewriting, we will ultimately delete the code we inserted. This
+ // means we need to revisit that PHI to make sure we extract out the
+ // needed piece.
+ if (PHINode *OldInVal = dyn_cast<PHINode>(PN->getIncomingValue(i)))
+ if (PHIsInspected.count(OldInVal)) {
+ unsigned RefPHIId = std::find(PHIsToSlice.begin(),PHIsToSlice.end(),
+ OldInVal)-PHIsToSlice.begin();
+ PHIUsers.push_back(PHIUsageRecord(RefPHIId, Offset,
+ cast<Instruction>(Res)));
+ ++UserE;
+ }
+ }
+ PredValues.clear();
+
+ DEBUG(errs() << " Made element PHI for offset " << Offset << ": "
+ << *EltPHI << '\n');
+ ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)] = EltPHI;
+ }
+
+ // Replace the use of this piece with the PHI node.
+ ReplaceInstUsesWith(*PHIUsers[UserI].Inst, EltPHI);
+ }
+
+ // Replace all the remaining uses of the PHI nodes (self uses and the lshrs)
+ // with undefs.
+ Value *Undef = UndefValue::get(FirstPhi.getType());
+ for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i)
+ ReplaceInstUsesWith(*PHIsToSlice[i], Undef);
+ return ReplaceInstUsesWith(FirstPhi, Undef);
+}
+
+// PHINode simplification
+//
+Instruction *InstCombiner::visitPHINode(PHINode &PN) {
+ // If LCSSA is around, don't mess with Phi nodes
+ if (MustPreserveLCSSA) return 0;
+
+ if (Value *V = PN.hasConstantValue())
+ return ReplaceInstUsesWith(PN, V);
+
+ // If all PHI operands are the same operation, pull them through the PHI,
+ // reducing code size.
+ if (isa<Instruction>(PN.getIncomingValue(0)) &&
+ isa<Instruction>(PN.getIncomingValue(1)) &&
+ cast<Instruction>(PN.getIncomingValue(0))->getOpcode() ==
+ cast<Instruction>(PN.getIncomingValue(1))->getOpcode() &&
+ // FIXME: The hasOneUse check will fail for PHIs that use the value more
+ // than themselves more than once.
+ PN.getIncomingValue(0)->hasOneUse())
+ if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
+ return Result;
+
+ // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
+ // this PHI only has a single use (a PHI), and if that PHI only has one use (a
+ // PHI)... break the cycle.
+ if (PN.hasOneUse()) {
+ Instruction *PHIUser = cast<Instruction>(PN.use_back());
+ if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) {
+ SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs;
+ PotentiallyDeadPHIs.insert(&PN);
+ if (DeadPHICycle(PU, PotentiallyDeadPHIs))
+ return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
+ }
+
+ // If this phi has a single use, and if that use just computes a value for
+ // the next iteration of a loop, delete the phi. This occurs with unused
+ // induction variables, e.g. "for (int j = 0; ; ++j);". Detecting this
+ // common case here is good because the only other things that catch this
+ // are induction variable analysis (sometimes) and ADCE, which is only run
+ // late.
+ if (PHIUser->hasOneUse() &&
+ (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) &&
+ PHIUser->use_back() == &PN) {
+ return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
+ }
+ }
+
+ // We sometimes end up with phi cycles that non-obviously end up being the
+ // same value, for example:
+ // z = some value; x = phi (y, z); y = phi (x, z)
+ // where the phi nodes don't necessarily need to be in the same block. Do a
+ // quick check to see if the PHI node only contains a single non-phi value, if
+ // so, scan to see if the phi cycle is actually equal to that value.
+ {
+ unsigned InValNo = 0, NumOperandVals = PN.getNumIncomingValues();
+ // Scan for the first non-phi operand.
+ while (InValNo != NumOperandVals &&
+ isa<PHINode>(PN.getIncomingValue(InValNo)))
+ ++InValNo;
+
+ if (InValNo != NumOperandVals) {
+ Value *NonPhiInVal = PN.getOperand(InValNo);
+
+ // Scan the rest of the operands to see if there are any conflicts, if so
+ // there is no need to recursively scan other phis.
+ for (++InValNo; InValNo != NumOperandVals; ++InValNo) {
+ Value *OpVal = PN.getIncomingValue(InValNo);
+ if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal))
+ break;
+ }
+
+ // If we scanned over all operands, then we have one unique value plus
+ // phi values. Scan PHI nodes to see if they all merge in each other or
+ // the value.
+ if (InValNo == NumOperandVals) {
+ SmallPtrSet<PHINode*, 16> ValueEqualPHIs;
+ if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs))
+ return ReplaceInstUsesWith(PN, NonPhiInVal);
+ }
+ }
+ }
+
+ // If there are multiple PHIs, sort their operands so that they all list
+ // the blocks in the same order. This will help identical PHIs be eliminated
+ // by other passes. Other passes shouldn't depend on this for correctness
+ // however.
+ PHINode *FirstPN = cast<PHINode>(PN.getParent()->begin());
+ if (&PN != FirstPN)
+ for (unsigned i = 0, e = FirstPN->getNumIncomingValues(); i != e; ++i) {
+ BasicBlock *BBA = PN.getIncomingBlock(i);
+ BasicBlock *BBB = FirstPN->getIncomingBlock(i);
+ if (BBA != BBB) {
+ Value *VA = PN.getIncomingValue(i);
+ unsigned j = PN.getBasicBlockIndex(BBB);
+ Value *VB = PN.getIncomingValue(j);
+ PN.setIncomingBlock(i, BBB);
+ PN.setIncomingValue(i, VB);
+ PN.setIncomingBlock(j, BBA);
+ PN.setIncomingValue(j, VA);
+ // NOTE: Instcombine normally would want us to "return &PN" if we
+ // modified any of the operands of an instruction. However, since we
+ // aren't adding or removing uses (just rearranging them) we don't do
+ // this in this case.
+ }
+ }
+
+ // If this is an integer PHI and we know that it has an illegal type, see if
+ // it is only used by trunc or trunc(lshr) operations. If so, we split the
+ // PHI into the various pieces being extracted. This sort of thing is
+ // introduced when SROA promotes an aggregate to a single large integer type.
+ if (isa<IntegerType>(PN.getType()) && TD &&
+ !TD->isLegalInteger(PN.getType()->getPrimitiveSizeInBits()))
+ if (Instruction *Res = SliceUpIllegalIntegerPHI(PN))
+ return Res;
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
+ SmallVector<Value*, 8> Ops(GEP.op_begin(), GEP.op_end());
+
+ if (Value *V = SimplifyGEPInst(&Ops[0], Ops.size(), TD))
+ return ReplaceInstUsesWith(GEP, V);
+
+ Value *PtrOp = GEP.getOperand(0);
+
+ if (isa<UndefValue>(GEP.getOperand(0)))
+ return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
+
+ // Eliminate unneeded casts for indices.
+ if (TD) {
+ bool MadeChange = false;
+ unsigned PtrSize = TD->getPointerSizeInBits();
+
+ gep_type_iterator GTI = gep_type_begin(GEP);
+ for (User::op_iterator I = GEP.op_begin() + 1, E = GEP.op_end();
+ I != E; ++I, ++GTI) {
+ if (!isa<SequentialType>(*GTI)) continue;
+
+ // If we are using a wider index than needed for this platform, shrink it
+ // to what we need. If narrower, sign-extend it to what we need. This
+ // explicit cast can make subsequent optimizations more obvious.
+ unsigned OpBits = cast<IntegerType>((*I)->getType())->getBitWidth();
+ if (OpBits == PtrSize)
+ continue;
+
+ *I = Builder->CreateIntCast(*I, TD->getIntPtrType(GEP.getContext()),true);
+ MadeChange = true;
+ }
+ if (MadeChange) return &GEP;
+ }
+
+ // Combine Indices - If the source pointer to this getelementptr instruction
+ // is a getelementptr instruction, combine the indices of the two
+ // getelementptr instructions into a single instruction.
+ //
+ if (GEPOperator *Src = dyn_cast<GEPOperator>(PtrOp)) {
+ // Note that if our source is a gep chain itself that we wait for that
+ // chain to be resolved before we perform this transformation. This
+ // avoids us creating a TON of code in some cases.
+ //
+ if (GetElementPtrInst *SrcGEP =
+ dyn_cast<GetElementPtrInst>(Src->getOperand(0)))
+ if (SrcGEP->getNumOperands() == 2)
+ return 0; // Wait until our source is folded to completion.
+
+ SmallVector<Value*, 8> Indices;
+
+ // Find out whether the last index in the source GEP is a sequential idx.
+ bool EndsWithSequential = false;
+ for (gep_type_iterator I = gep_type_begin(*Src), E = gep_type_end(*Src);
+ I != E; ++I)
+ EndsWithSequential = !isa<StructType>(*I);
+
+ // Can we combine the two pointer arithmetics offsets?
+ if (EndsWithSequential) {
+ // Replace: gep (gep %P, long B), long A, ...
+ // With: T = long A+B; gep %P, T, ...
+ //
+ Value *Sum;
+ Value *SO1 = Src->getOperand(Src->getNumOperands()-1);
+ Value *GO1 = GEP.getOperand(1);
+ if (SO1 == Constant::getNullValue(SO1->getType())) {
+ Sum = GO1;
+ } else if (GO1 == Constant::getNullValue(GO1->getType())) {
+ Sum = SO1;
+ } else {
+ // If they aren't the same type, then the input hasn't been processed
+ // by the loop above yet (which canonicalizes sequential index types to
+ // intptr_t). Just avoid transforming this until the input has been
+ // normalized.
+ if (SO1->getType() != GO1->getType())
+ return 0;
+ Sum = Builder->CreateAdd(SO1, GO1, PtrOp->getName()+".sum");
+ }
+
+ // Update the GEP in place if possible.
+ if (Src->getNumOperands() == 2) {
+ GEP.setOperand(0, Src->getOperand(0));
+ GEP.setOperand(1, Sum);
+ return &GEP;
+ }
+ Indices.append(Src->op_begin()+1, Src->op_end()-1);
+ Indices.push_back(Sum);
+ Indices.append(GEP.op_begin()+2, GEP.op_end());
+ } else if (isa<Constant>(*GEP.idx_begin()) &&
+ cast<Constant>(*GEP.idx_begin())->isNullValue() &&
+ Src->getNumOperands() != 1) {
+ // Otherwise we can do the fold if the first index of the GEP is a zero
+ Indices.append(Src->op_begin()+1, Src->op_end());
+ Indices.append(GEP.idx_begin()+1, GEP.idx_end());
+ }
+
+ if (!Indices.empty())
+ return (cast<GEPOperator>(&GEP)->isInBounds() &&
+ Src->isInBounds()) ?
+ GetElementPtrInst::CreateInBounds(Src->getOperand(0), Indices.begin(),
+ Indices.end(), GEP.getName()) :
+ GetElementPtrInst::Create(Src->getOperand(0), Indices.begin(),
+ Indices.end(), GEP.getName());
+ }
+
+ // Handle gep(bitcast x) and gep(gep x, 0, 0, 0).
+ if (Value *X = getBitCastOperand(PtrOp)) {
+ assert(isa<PointerType>(X->getType()) && "Must be cast from pointer");
+
+ // If the input bitcast is actually "bitcast(bitcast(x))", then we don't
+ // want to change the gep until the bitcasts are eliminated.
+ if (getBitCastOperand(X)) {
+ Worklist.AddValue(PtrOp);
+ return 0;
+ }
+
+ bool HasZeroPointerIndex = false;
+ if (ConstantInt *C = dyn_cast<ConstantInt>(GEP.getOperand(1)))
+ HasZeroPointerIndex = C->isZero();
+
+ // Transform: GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ...
+ // into : GEP [10 x i8]* X, i32 0, ...
+ //
+ // Likewise, transform: GEP (bitcast i8* X to [0 x i8]*), i32 0, ...
+ // into : GEP i8* X, ...
+ //
+ // This occurs when the program declares an array extern like "int X[];"
+ if (HasZeroPointerIndex) {
+ const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
+ const PointerType *XTy = cast<PointerType>(X->getType());
+ if (const ArrayType *CATy =
+ dyn_cast<ArrayType>(CPTy->getElementType())) {
+ // GEP (bitcast i8* X to [0 x i8]*), i32 0, ... ?
+ if (CATy->getElementType() == XTy->getElementType()) {
+ // -> GEP i8* X, ...
+ SmallVector<Value*, 8> Indices(GEP.idx_begin()+1, GEP.idx_end());
+ return cast<GEPOperator>(&GEP)->isInBounds() ?
+ GetElementPtrInst::CreateInBounds(X, Indices.begin(), Indices.end(),
+ GEP.getName()) :
+ GetElementPtrInst::Create(X, Indices.begin(), Indices.end(),
+ GEP.getName());
+ }
+
+ if (const ArrayType *XATy = dyn_cast<ArrayType>(XTy->getElementType())){
+ // GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ... ?
+ if (CATy->getElementType() == XATy->getElementType()) {
+ // -> GEP [10 x i8]* X, i32 0, ...
+ // At this point, we know that the cast source type is a pointer
+ // to an array of the same type as the destination pointer
+ // array. Because the array type is never stepped over (there
+ // is a leading zero) we can fold the cast into this GEP.
+ GEP.setOperand(0, X);
+ return &GEP;
+ }
+ }
+ }
+ } else if (GEP.getNumOperands() == 2) {
+ // Transform things like:
+ // %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V
+ // into: %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast
+ const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
+ const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
+ if (TD && isa<ArrayType>(SrcElTy) &&
+ TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
+ TD->getTypeAllocSize(ResElTy)) {
+ Value *Idx[2];
+ Idx[0] = Constant::getNullValue(Type::getInt32Ty(*Context));
+ Idx[1] = GEP.getOperand(1);
+ Value *NewGEP = cast<GEPOperator>(&GEP)->isInBounds() ?
+ Builder->CreateInBoundsGEP(X, Idx, Idx + 2, GEP.getName()) :
+ Builder->CreateGEP(X, Idx, Idx + 2, GEP.getName());
+ // V and GEP are both pointer types --> BitCast
+ return new BitCastInst(NewGEP, GEP.getType());
+ }
+
+ // Transform things like:
+ // getelementptr i8* bitcast ([100 x double]* X to i8*), i32 %tmp
+ // (where tmp = 8*tmp2) into:
+ // getelementptr [100 x double]* %arr, i32 0, i32 %tmp2; bitcast
+
+ if (TD && isa<ArrayType>(SrcElTy) && ResElTy == Type::getInt8Ty(*Context)) {
+ uint64_t ArrayEltSize =
+ TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType());
+
+ // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
+ // allow either a mul, shift, or constant here.
+ Value *NewIdx = 0;
+ ConstantInt *Scale = 0;
+ if (ArrayEltSize == 1) {
+ NewIdx = GEP.getOperand(1);
+ Scale = ConstantInt::get(cast<IntegerType>(NewIdx->getType()), 1);
+ } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
+ NewIdx = ConstantInt::get(CI->getType(), 1);
+ Scale = CI;
+ } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
+ if (Inst->getOpcode() == Instruction::Shl &&
+ isa<ConstantInt>(Inst->getOperand(1))) {
+ ConstantInt *ShAmt = cast<ConstantInt>(Inst->getOperand(1));
+ uint32_t ShAmtVal = ShAmt->getLimitedValue(64);
+ Scale = ConstantInt::get(cast<IntegerType>(Inst->getType()),
+ 1ULL << ShAmtVal);
+ NewIdx = Inst->getOperand(0);
+ } else if (Inst->getOpcode() == Instruction::Mul &&
+ isa<ConstantInt>(Inst->getOperand(1))) {
+ Scale = cast<ConstantInt>(Inst->getOperand(1));
+ NewIdx = Inst->getOperand(0);
+ }
+ }
+
+ // If the index will be to exactly the right offset with the scale taken
+ // out, perform the transformation. Note, we don't know whether Scale is
+ // signed or not. We'll use unsigned version of division/modulo
+ // operation after making sure Scale doesn't have the sign bit set.
+ if (ArrayEltSize && Scale && Scale->getSExtValue() >= 0LL &&
+ Scale->getZExtValue() % ArrayEltSize == 0) {
+ Scale = ConstantInt::get(Scale->getType(),
+ Scale->getZExtValue() / ArrayEltSize);
+ if (Scale->getZExtValue() != 1) {
+ Constant *C = ConstantExpr::getIntegerCast(Scale, NewIdx->getType(),
+ false /*ZExt*/);
+ NewIdx = Builder->CreateMul(NewIdx, C, "idxscale");
+ }
+
+ // Insert the new GEP instruction.
+ Value *Idx[2];
+ Idx[0] = Constant::getNullValue(Type::getInt32Ty(*Context));
+ Idx[1] = NewIdx;
+ Value *NewGEP = cast<GEPOperator>(&GEP)->isInBounds() ?
+ Builder->CreateInBoundsGEP(X, Idx, Idx + 2, GEP.getName()) :
+ Builder->CreateGEP(X, Idx, Idx + 2, GEP.getName());
+ // The NewGEP must be pointer typed, so must the old one -> BitCast
+ return new BitCastInst(NewGEP, GEP.getType());
+ }
+ }
+ }
+ }
+
+ /// See if we can simplify:
+ /// X = bitcast A* to B*
+ /// Y = gep X, <...constant indices...>
+ /// into a gep of the original struct. This is important for SROA and alias
+ /// analysis of unions. If "A" is also a bitcast, wait for A/X to be merged.
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
+ if (TD &&
+ !isa<BitCastInst>(BCI->getOperand(0)) && GEP.hasAllConstantIndices()) {
+ // Determine how much the GEP moves the pointer. We are guaranteed to get
+ // a constant back from EmitGEPOffset.
+ ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(&GEP, *this));
+ int64_t Offset = OffsetV->getSExtValue();
+
+ // If this GEP instruction doesn't move the pointer, just replace the GEP
+ // with a bitcast of the real input to the dest type.
+ if (Offset == 0) {
+ // If the bitcast is of an allocation, and the allocation will be
+ // converted to match the type of the cast, don't touch this.
+ if (isa<AllocaInst>(BCI->getOperand(0)) ||
+ isMalloc(BCI->getOperand(0))) {
+ // See if the bitcast simplifies, if so, don't nuke this GEP yet.
+ if (Instruction *I = visitBitCast(*BCI)) {
+ if (I != BCI) {
+ I->takeName(BCI);
+ BCI->getParent()->getInstList().insert(BCI, I);
+ ReplaceInstUsesWith(*BCI, I);
+ }
+ return &GEP;
+ }
+ }
+ return new BitCastInst(BCI->getOperand(0), GEP.getType());
+ }
+
+ // Otherwise, if the offset is non-zero, we need to find out if there is a
+ // field at Offset in 'A's type. If so, we can pull the cast through the
+ // GEP.
+ SmallVector<Value*, 8> NewIndices;
+ const Type *InTy =
+ cast<PointerType>(BCI->getOperand(0)->getType())->getElementType();
+ if (FindElementAtOffset(InTy, Offset, NewIndices, TD, Context)) {
+ Value *NGEP = cast<GEPOperator>(&GEP)->isInBounds() ?
+ Builder->CreateInBoundsGEP(BCI->getOperand(0), NewIndices.begin(),
+ NewIndices.end()) :
+ Builder->CreateGEP(BCI->getOperand(0), NewIndices.begin(),
+ NewIndices.end());
+
+ if (NGEP->getType() == GEP.getType())
+ return ReplaceInstUsesWith(GEP, NGEP);
+ NGEP->takeName(&GEP);
+ return new BitCastInst(NGEP, GEP.getType());
+ }
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) {
+ // Convert: alloca Ty, C - where C is a constant != 1 into: alloca [C x Ty], 1
+ if (AI.isArrayAllocation()) { // Check C != 1
+ if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
+ const Type *NewTy =
+ ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
+ assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
+ AllocaInst *New = Builder->CreateAlloca(NewTy, 0, AI.getName());
+ New->setAlignment(AI.getAlignment());
+
+ // Scan to the end of the allocation instructions, to skip over a block of
+ // allocas if possible...also skip interleaved debug info
+ //
+ BasicBlock::iterator It = New;
+ while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It)) ++It;
+
+ // Now that I is pointing to the first non-allocation-inst in the block,
+ // insert our getelementptr instruction...
+ //
+ Value *NullIdx = Constant::getNullValue(Type::getInt32Ty(*Context));
+ Value *Idx[2];
+ Idx[0] = NullIdx;
+ Idx[1] = NullIdx;
+ Value *V = GetElementPtrInst::CreateInBounds(New, Idx, Idx + 2,
+ New->getName()+".sub", It);
+
+ // Now make everything use the getelementptr instead of the original
+ // allocation.
+ return ReplaceInstUsesWith(AI, V);
+ } else if (isa<UndefValue>(AI.getArraySize())) {
+ return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
+ }
+ }
+
+ if (TD && isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized()) {
+ // If alloca'ing a zero byte object, replace the alloca with a null pointer.
+ // Note that we only do this for alloca's, because malloc should allocate
+ // and return a unique pointer, even for a zero byte allocation.
+ if (TD->getTypeAllocSize(AI.getAllocatedType()) == 0)
+ return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
+
+ // If the alignment is 0 (unspecified), assign it the preferred alignment.
+ if (AI.getAlignment() == 0)
+ AI.setAlignment(TD->getPrefTypeAlignment(AI.getAllocatedType()));
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitFree(Instruction &FI) {
+ Value *Op = FI.getOperand(1);
+
+ // free undef -> unreachable.
+ if (isa<UndefValue>(Op)) {
+ // Insert a new store to null because we cannot modify the CFG here.
+ new StoreInst(ConstantInt::getTrue(*Context),
+ UndefValue::get(Type::getInt1PtrTy(*Context)), &FI);
+ return EraseInstFromFunction(FI);
+ }
+
+ // If we have 'free null' delete the instruction. This can happen in stl code
+ // when lots of inlining happens.
+ if (isa<ConstantPointerNull>(Op))
+ return EraseInstFromFunction(FI);
+
+ // If we have a malloc call whose only use is a free call, delete both.
+ if (isMalloc(Op)) {
+ if (CallInst* CI = extractMallocCallFromBitCast(Op)) {
+ if (Op->hasOneUse() && CI->hasOneUse()) {
+ EraseInstFromFunction(FI);
+ EraseInstFromFunction(*CI);
+ return EraseInstFromFunction(*cast<Instruction>(Op));
+ }
+ } else {
+ // Op is a call to malloc
+ if (Op->hasOneUse()) {
+ EraseInstFromFunction(FI);
+ return EraseInstFromFunction(*cast<Instruction>(Op));
+ }
+ }
+ }
+
+ return 0;
+}
+
+/// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
+static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
+ const TargetData *TD) {
+ User *CI = cast<User>(LI.getOperand(0));
+ Value *CastOp = CI->getOperand(0);
+ LLVMContext *Context = IC.getContext();
+
+ const PointerType *DestTy = cast<PointerType>(CI->getType());
+ const Type *DestPTy = DestTy->getElementType();
+ if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
+
+ // If the address spaces don't match, don't eliminate the cast.
+ if (DestTy->getAddressSpace() != SrcTy->getAddressSpace())
+ return 0;
+
+ const Type *SrcPTy = SrcTy->getElementType();
+
+ if (DestPTy->isInteger() || isa<PointerType>(DestPTy) ||
+ isa<VectorType>(DestPTy)) {
+ // If the source is an array, the code below will not succeed. Check to
+ // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
+ // constants.
+ if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
+ if (Constant *CSrc = dyn_cast<Constant>(CastOp))
+ if (ASrcTy->getNumElements() != 0) {
+ Value *Idxs[2];
+ Idxs[0] = Constant::getNullValue(Type::getInt32Ty(*Context));
+ Idxs[1] = Idxs[0];
+ CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
+ SrcTy = cast<PointerType>(CastOp->getType());
+ SrcPTy = SrcTy->getElementType();
+ }
+
+ if (IC.getTargetData() &&
+ (SrcPTy->isInteger() || isa<PointerType>(SrcPTy) ||
+ isa<VectorType>(SrcPTy)) &&
+ // Do not allow turning this into a load of an integer, which is then
+ // casted to a pointer, this pessimizes pointer analysis a lot.
+ (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
+ IC.getTargetData()->getTypeSizeInBits(SrcPTy) ==
+ IC.getTargetData()->getTypeSizeInBits(DestPTy)) {
+
+ // Okay, we are casting from one integer or pointer type to another of
+ // the same size. Instead of casting the pointer before the load, cast
+ // the result of the loaded value.
+ Value *NewLoad =
+ IC.Builder->CreateLoad(CastOp, LI.isVolatile(), CI->getName());
+ // Now cast the result of the load.
+ return new BitCastInst(NewLoad, LI.getType());
+ }
+ }
+ }
+ return 0;
+}
+
+Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
+ Value *Op = LI.getOperand(0);
+
+ // Attempt to improve the alignment.
+ if (TD) {
+ unsigned KnownAlign =
+ GetOrEnforceKnownAlignment(Op, TD->getPrefTypeAlignment(LI.getType()));
+ if (KnownAlign >
+ (LI.getAlignment() == 0 ? TD->getABITypeAlignment(LI.getType()) :
+ LI.getAlignment()))
+ LI.setAlignment(KnownAlign);
+ }
+
+ // load (cast X) --> cast (load X) iff safe.
+ if (isa<CastInst>(Op))
+ if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
+ return Res;
+
+ // None of the following transforms are legal for volatile loads.
+ if (LI.isVolatile()) return 0;
+
+ // Do really simple store-to-load forwarding and load CSE, to catch cases
+ // where there are several consequtive memory accesses to the same location,
+ // separated by a few arithmetic operations.
+ BasicBlock::iterator BBI = &LI;
+ if (Value *AvailableVal = FindAvailableLoadedValue(Op, LI.getParent(), BBI,6))
+ return ReplaceInstUsesWith(LI, AvailableVal);
+
+ // load(gep null, ...) -> unreachable
+ if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
+ const Value *GEPI0 = GEPI->getOperand(0);
+ // TODO: Consider a target hook for valid address spaces for this xform.
+ if (isa<ConstantPointerNull>(GEPI0) && GEPI->getPointerAddressSpace() == 0){
+ // Insert a new store to null instruction before the load to indicate
+ // that this code is not reachable. We do this instead of inserting
+ // an unreachable instruction directly because we cannot modify the
+ // CFG.
+ new StoreInst(UndefValue::get(LI.getType()),
+ Constant::getNullValue(Op->getType()), &LI);
+ return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
+ }
+ }
+
+ // load null/undef -> unreachable
+ // TODO: Consider a target hook for valid address spaces for this xform.
+ if (isa<UndefValue>(Op) ||
+ (isa<ConstantPointerNull>(Op) && LI.getPointerAddressSpace() == 0)) {
+ // Insert a new store to null instruction before the load to indicate that
+ // this code is not reachable. We do this instead of inserting an
+ // unreachable instruction directly because we cannot modify the CFG.
+ new StoreInst(UndefValue::get(LI.getType()),
+ Constant::getNullValue(Op->getType()), &LI);
+ return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
+ }
+
+ // Instcombine load (constantexpr_cast global) -> cast (load global)
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
+ if (CE->isCast())
+ if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
+ return Res;
+
+ if (Op->hasOneUse()) {
+ // Change select and PHI nodes to select values instead of addresses: this
+ // helps alias analysis out a lot, allows many others simplifications, and
+ // exposes redundancy in the code.
+ //
+ // Note that we cannot do the transformation unless we know that the
+ // introduced loads cannot trap! Something like this is valid as long as
+ // the condition is always false: load (select bool %C, int* null, int* %G),
+ // but it would not be valid if we transformed it to load from null
+ // unconditionally.
+ //
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
+ // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
+ if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
+ isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
+ Value *V1 = Builder->CreateLoad(SI->getOperand(1),
+ SI->getOperand(1)->getName()+".val");
+ Value *V2 = Builder->CreateLoad(SI->getOperand(2),
+ SI->getOperand(2)->getName()+".val");
+ return SelectInst::Create(SI->getCondition(), V1, V2);
+ }
+
+ // load (select (cond, null, P)) -> load P
+ if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
+ if (C->isNullValue()) {
+ LI.setOperand(0, SI->getOperand(2));
+ return &LI;
+ }
+
+ // load (select (cond, P, null)) -> load P
+ if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
+ if (C->isNullValue()) {
+ LI.setOperand(0, SI->getOperand(1));
+ return &LI;
+ }
+ }
+ }
+ return 0;
+}
+
+/// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast V), P
+/// when possible. This makes it generally easy to do alias analysis and/or
+/// SROA/mem2reg of the memory object.
+static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
+ User *CI = cast<User>(SI.getOperand(1));
+ Value *CastOp = CI->getOperand(0);
+
+ const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
+ const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType());
+ if (SrcTy == 0) return 0;
+
+ const Type *SrcPTy = SrcTy->getElementType();
+
+ if (!DestPTy->isInteger() && !isa<PointerType>(DestPTy))
+ return 0;
+
+ /// NewGEPIndices - If SrcPTy is an aggregate type, we can emit a "noop gep"
+ /// to its first element. This allows us to handle things like:
+ /// store i32 xxx, (bitcast {foo*, float}* %P to i32*)
+ /// on 32-bit hosts.
+ SmallVector<Value*, 4> NewGEPIndices;
+
+ // If the source is an array, the code below will not succeed. Check to
+ // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
+ // constants.
+ if (isa<ArrayType>(SrcPTy) || isa<StructType>(SrcPTy)) {
+ // Index through pointer.
+ Constant *Zero = Constant::getNullValue(Type::getInt32Ty(*IC.getContext()));
+ NewGEPIndices.push_back(Zero);
+
+ while (1) {
+ if (const StructType *STy = dyn_cast<StructType>(SrcPTy)) {
+ if (!STy->getNumElements()) /* Struct can be empty {} */
+ break;
+ NewGEPIndices.push_back(Zero);
+ SrcPTy = STy->getElementType(0);
+ } else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcPTy)) {
+ NewGEPIndices.push_back(Zero);
+ SrcPTy = ATy->getElementType();
+ } else {
+ break;
+ }
+ }
+
+ SrcTy = PointerType::get(SrcPTy, SrcTy->getAddressSpace());
+ }
+
+ if (!SrcPTy->isInteger() && !isa<PointerType>(SrcPTy))
+ return 0;
+
+ // If the pointers point into different address spaces or if they point to
+ // values with different sizes, we can't do the transformation.
+ if (!IC.getTargetData() ||
+ SrcTy->getAddressSpace() !=
+ cast<PointerType>(CI->getType())->getAddressSpace() ||
+ IC.getTargetData()->getTypeSizeInBits(SrcPTy) !=
+ IC.getTargetData()->getTypeSizeInBits(DestPTy))
+ return 0;
+
+ // Okay, we are casting from one integer or pointer type to another of
+ // the same size. Instead of casting the pointer before
+ // the store, cast the value to be stored.
+ Value *NewCast;
+ Value *SIOp0 = SI.getOperand(0);
+ Instruction::CastOps opcode = Instruction::BitCast;
+ const Type* CastSrcTy = SIOp0->getType();
+ const Type* CastDstTy = SrcPTy;
+ if (isa<PointerType>(CastDstTy)) {
+ if (CastSrcTy->isInteger())
+ opcode = Instruction::IntToPtr;
+ } else if (isa<IntegerType>(CastDstTy)) {
+ if (isa<PointerType>(SIOp0->getType()))
+ opcode = Instruction::PtrToInt;
+ }
+
+ // SIOp0 is a pointer to aggregate and this is a store to the first field,
+ // emit a GEP to index into its first field.
+ if (!NewGEPIndices.empty())
+ CastOp = IC.Builder->CreateInBoundsGEP(CastOp, NewGEPIndices.begin(),
+ NewGEPIndices.end());
+
+ NewCast = IC.Builder->CreateCast(opcode, SIOp0, CastDstTy,
+ SIOp0->getName()+".c");
+ return new StoreInst(NewCast, CastOp);
+}
+
+/// equivalentAddressValues - Test if A and B will obviously have the same
+/// value. This includes recognizing that %t0 and %t1 will have the same
+/// value in code like this:
+/// %t0 = getelementptr \@a, 0, 3
+/// store i32 0, i32* %t0
+/// %t1 = getelementptr \@a, 0, 3
+/// %t2 = load i32* %t1
+///
+static bool equivalentAddressValues(Value *A, Value *B) {
+ // Test if the values are trivially equivalent.
+ if (A == B) return true;
+
+ // Test if the values come form identical arithmetic instructions.
+ // This uses isIdenticalToWhenDefined instead of isIdenticalTo because
+ // its only used to compare two uses within the same basic block, which
+ // means that they'll always either have the same value or one of them
+ // will have an undefined value.
+ if (isa<BinaryOperator>(A) ||
+ isa<CastInst>(A) ||
+ isa<PHINode>(A) ||
+ isa<GetElementPtrInst>(A))
+ if (Instruction *BI = dyn_cast<Instruction>(B))
+ if (cast<Instruction>(A)->isIdenticalToWhenDefined(BI))
+ return true;
+
+ // Otherwise they may not be equivalent.
+ return false;
+}
+
+// If this instruction has two uses, one of which is a llvm.dbg.declare,
+// return the llvm.dbg.declare.
+DbgDeclareInst *InstCombiner::hasOneUsePlusDeclare(Value *V) {
+ if (!V->hasNUses(2))
+ return 0;
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
+ UI != E; ++UI) {
+ if (DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(UI))
+ return DI;
+ if (isa<BitCastInst>(UI) && UI->hasOneUse()) {
+ if (DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(UI->use_begin()))
+ return DI;
+ }
+ }
+ return 0;
+}
+
+Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
+ Value *Val = SI.getOperand(0);
+ Value *Ptr = SI.getOperand(1);
+
+ // If the RHS is an alloca with a single use, zapify the store, making the
+ // alloca dead.
+ // If the RHS is an alloca with a two uses, the other one being a
+ // llvm.dbg.declare, zapify the store and the declare, making the
+ // alloca dead. We must do this to prevent declare's from affecting
+ // codegen.
+ if (!SI.isVolatile()) {
+ if (Ptr->hasOneUse()) {
+ if (isa<AllocaInst>(Ptr)) {
+ EraseInstFromFunction(SI);
+ ++NumCombined;
+ return 0;
+ }
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
+ if (isa<AllocaInst>(GEP->getOperand(0))) {
+ if (GEP->getOperand(0)->hasOneUse()) {
+ EraseInstFromFunction(SI);
+ ++NumCombined;
+ return 0;
+ }
+ if (DbgDeclareInst *DI = hasOneUsePlusDeclare(GEP->getOperand(0))) {
+ EraseInstFromFunction(*DI);
+ EraseInstFromFunction(SI);
+ ++NumCombined;
+ return 0;
+ }
+ }
+ }
+ }
+ if (DbgDeclareInst *DI = hasOneUsePlusDeclare(Ptr)) {
+ EraseInstFromFunction(*DI);
+ EraseInstFromFunction(SI);
+ ++NumCombined;
+ return 0;
+ }
+ }
+
+ // Attempt to improve the alignment.
+ if (TD) {
+ unsigned KnownAlign =
+ GetOrEnforceKnownAlignment(Ptr, TD->getPrefTypeAlignment(Val->getType()));
+ if (KnownAlign >
+ (SI.getAlignment() == 0 ? TD->getABITypeAlignment(Val->getType()) :
+ SI.getAlignment()))
+ SI.setAlignment(KnownAlign);
+ }
+
+ // Do really simple DSE, to catch cases where there are several consecutive
+ // stores to the same location, separated by a few arithmetic operations. This
+ // situation often occurs with bitfield accesses.
+ BasicBlock::iterator BBI = &SI;
+ for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
+ --ScanInsts) {
+ --BBI;
+ // Don't count debug info directives, lest they affect codegen,
+ // and we skip pointer-to-pointer bitcasts, which are NOPs.
+ // It is necessary for correctness to skip those that feed into a
+ // llvm.dbg.declare, as these are not present when debugging is off.
+ if (isa<DbgInfoIntrinsic>(BBI) ||
+ (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType()))) {
+ ScanInsts++;
+ continue;
+ }
+
+ if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
+ // Prev store isn't volatile, and stores to the same location?
+ if (!PrevSI->isVolatile() &&equivalentAddressValues(PrevSI->getOperand(1),
+ SI.getOperand(1))) {
+ ++NumDeadStore;
+ ++BBI;
+ EraseInstFromFunction(*PrevSI);
+ continue;
+ }
+ break;
+ }
+
+ // If this is a load, we have to stop. However, if the loaded value is from
+ // the pointer we're loading and is producing the pointer we're storing,
+ // then *this* store is dead (X = load P; store X -> P).
+ if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
+ if (LI == Val && equivalentAddressValues(LI->getOperand(0), Ptr) &&
+ !SI.isVolatile()) {
+ EraseInstFromFunction(SI);
+ ++NumCombined;
+ return 0;
+ }
+ // Otherwise, this is a load from some other location. Stores before it
+ // may not be dead.
+ break;
+ }
+
+ // Don't skip over loads or things that can modify memory.
+ if (BBI->mayWriteToMemory() || BBI->mayReadFromMemory())
+ break;
+ }
+
+
+ if (SI.isVolatile()) return 0; // Don't hack volatile stores.
+
+ // store X, null -> turns into 'unreachable' in SimplifyCFG
+ if (isa<ConstantPointerNull>(Ptr) && SI.getPointerAddressSpace() == 0) {
+ if (!isa<UndefValue>(Val)) {
+ SI.setOperand(0, UndefValue::get(Val->getType()));
+ if (Instruction *U = dyn_cast<Instruction>(Val))
+ Worklist.Add(U); // Dropped a use.
+ ++NumCombined;
+ }
+ return 0; // Do not modify these!
+ }
+
+ // store undef, Ptr -> noop
+ if (isa<UndefValue>(Val)) {
+ EraseInstFromFunction(SI);
+ ++NumCombined;
+ return 0;
+ }
+
+ // If the pointer destination is a cast, see if we can fold the cast into the
+ // source instead.
+ if (isa<CastInst>(Ptr))
+ if (Instruction *Res = InstCombineStoreToCast(*this, SI))
+ return Res;
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+ if (CE->isCast())
+ if (Instruction *Res = InstCombineStoreToCast(*this, SI))
+ return Res;
+
+
+ // If this store is the last instruction in the basic block (possibly
+ // excepting debug info instructions and the pointer bitcasts that feed
+ // into them), and if the block ends with an unconditional branch, try
+ // to move it to the successor block.
+ BBI = &SI;
+ do {
+ ++BBI;
+ } while (isa<DbgInfoIntrinsic>(BBI) ||
+ (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType())));
+ if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
+ if (BI->isUnconditional())
+ if (SimplifyStoreAtEndOfBlock(SI))
+ return 0; // xform done!
+
+ return 0;
+}
+
+/// SimplifyStoreAtEndOfBlock - Turn things like:
+/// if () { *P = v1; } else { *P = v2 }
+/// into a phi node with a store in the successor.
+///
+/// Simplify things like:
+/// *P = v1; if () { *P = v2; }
+/// into a phi node with a store in the successor.
+///
+bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
+ BasicBlock *StoreBB = SI.getParent();
+
+ // Check to see if the successor block has exactly two incoming edges. If
+ // so, see if the other predecessor contains a store to the same location.
+ // if so, insert a PHI node (if needed) and move the stores down.
+ BasicBlock *DestBB = StoreBB->getTerminator()->getSuccessor(0);
+
+ // Determine whether Dest has exactly two predecessors and, if so, compute
+ // the other predecessor.
+ pred_iterator PI = pred_begin(DestBB);
+ BasicBlock *OtherBB = 0;
+ if (*PI != StoreBB)
+ OtherBB = *PI;
+ ++PI;
+ if (PI == pred_end(DestBB))
+ return false;
+
+ if (*PI != StoreBB) {
+ if (OtherBB)
+ return false;
+ OtherBB = *PI;
+ }
+ if (++PI != pred_end(DestBB))
+ return false;
+
+ // Bail out if all the relevant blocks aren't distinct (this can happen,
+ // for example, if SI is in an infinite loop)
+ if (StoreBB == DestBB || OtherBB == DestBB)
+ return false;
+
+ // Verify that the other block ends in a branch and is not otherwise empty.
+ BasicBlock::iterator BBI = OtherBB->getTerminator();
+ BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
+ if (!OtherBr || BBI == OtherBB->begin())
+ return false;
+
+ // If the other block ends in an unconditional branch, check for the 'if then
+ // else' case. there is an instruction before the branch.
+ StoreInst *OtherStore = 0;
+ if (OtherBr->isUnconditional()) {
+ --BBI;
+ // Skip over debugging info.
+ while (isa<DbgInfoIntrinsic>(BBI) ||
+ (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType()))) {
+ if (BBI==OtherBB->begin())
+ return false;
+ --BBI;
+ }
+ // If this isn't a store, isn't a store to the same location, or if the
+ // alignments differ, bail out.
+ OtherStore = dyn_cast<StoreInst>(BBI);
+ if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1) ||
+ OtherStore->getAlignment() != SI.getAlignment())
+ return false;
+ } else {
+ // Otherwise, the other block ended with a conditional branch. If one of the
+ // destinations is StoreBB, then we have the if/then case.
+ if (OtherBr->getSuccessor(0) != StoreBB &&
+ OtherBr->getSuccessor(1) != StoreBB)
+ return false;
+
+ // Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an
+ // if/then triangle. See if there is a store to the same ptr as SI that
+ // lives in OtherBB.
+ for (;; --BBI) {
+ // Check to see if we find the matching store.
+ if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
+ if (OtherStore->getOperand(1) != SI.getOperand(1) ||
+ OtherStore->getAlignment() != SI.getAlignment())
+ return false;
+ break;
+ }
+ // If we find something that may be using or overwriting the stored
+ // value, or if we run out of instructions, we can't do the xform.
+ if (BBI->mayReadFromMemory() || BBI->mayWriteToMemory() ||
+ BBI == OtherBB->begin())
+ return false;
+ }
+
+ // In order to eliminate the store in OtherBr, we have to
+ // make sure nothing reads or overwrites the stored value in
+ // StoreBB.
+ for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) {
+ // FIXME: This should really be AA driven.
+ if (I->mayReadFromMemory() || I->mayWriteToMemory())
+ return false;
+ }
+ }
+
+ // Insert a PHI node now if we need it.
+ Value *MergedVal = OtherStore->getOperand(0);
+ if (MergedVal != SI.getOperand(0)) {
+ PHINode *PN = PHINode::Create(MergedVal->getType(), "storemerge");
+ PN->reserveOperandSpace(2);
+ PN->addIncoming(SI.getOperand(0), SI.getParent());
+ PN->addIncoming(OtherStore->getOperand(0), OtherBB);
+ MergedVal = InsertNewInstBefore(PN, DestBB->front());
+ }
+
+ // Advance to a place where it is safe to insert the new store and
+ // insert it.
+ BBI = DestBB->getFirstNonPHI();
+ InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
+ OtherStore->isVolatile(),
+ SI.getAlignment()), *BBI);
+
+ // Nuke the old stores.
+ EraseInstFromFunction(SI);
+ EraseInstFromFunction(*OtherStore);
+ ++NumCombined;
+ return true;
+}
+
+
+Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
+ // Change br (not X), label True, label False to: br X, label False, True
+ Value *X = 0;
+ BasicBlock *TrueDest;
+ BasicBlock *FalseDest;
+ if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
+ !isa<Constant>(X)) {
+ // Swap Destinations and condition...
+ BI.setCondition(X);
+ BI.setSuccessor(0, FalseDest);
+ BI.setSuccessor(1, TrueDest);
+ return &BI;
+ }
+
+ // Cannonicalize fcmp_one -> fcmp_oeq
+ FCmpInst::Predicate FPred; Value *Y;
+ if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)),
+ TrueDest, FalseDest)) &&
+ BI.getCondition()->hasOneUse())
+ if (FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE ||
+ FPred == FCmpInst::FCMP_OGE) {
+ FCmpInst *Cond = cast<FCmpInst>(BI.getCondition());
+ Cond->setPredicate(FCmpInst::getInversePredicate(FPred));
+
+ // Swap Destinations and condition.
+ BI.setSuccessor(0, FalseDest);
+ BI.setSuccessor(1, TrueDest);
+ Worklist.Add(Cond);
+ return &BI;
+ }
+
+ // Cannonicalize icmp_ne -> icmp_eq
+ ICmpInst::Predicate IPred;
+ if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
+ TrueDest, FalseDest)) &&
+ BI.getCondition()->hasOneUse())
+ if (IPred == ICmpInst::ICMP_NE || IPred == ICmpInst::ICMP_ULE ||
+ IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE ||
+ IPred == ICmpInst::ICMP_SGE) {
+ ICmpInst *Cond = cast<ICmpInst>(BI.getCondition());
+ Cond->setPredicate(ICmpInst::getInversePredicate(IPred));
+ // Swap Destinations and condition.
+ BI.setSuccessor(0, FalseDest);
+ BI.setSuccessor(1, TrueDest);
+ Worklist.Add(Cond);
+ return &BI;
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
+ Value *Cond = SI.getCondition();
+ if (Instruction *I = dyn_cast<Instruction>(Cond)) {
+ if (I->getOpcode() == Instruction::Add)
+ if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ // change 'switch (X+4) case 1:' into 'switch (X) case -3'
+ for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
+ SI.setOperand(i,
+ ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
+ AddRHS));
+ SI.setOperand(0, I->getOperand(0));
+ Worklist.Add(I);
+ return &SI;
+ }
+ }
+ return 0;
+}
+
+Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) {
+ Value *Agg = EV.getAggregateOperand();
+
+ if (!EV.hasIndices())
+ return ReplaceInstUsesWith(EV, Agg);
+
+ if (Constant *C = dyn_cast<Constant>(Agg)) {
+ if (isa<UndefValue>(C))
+ return ReplaceInstUsesWith(EV, UndefValue::get(EV.getType()));
+
+ if (isa<ConstantAggregateZero>(C))
+ return ReplaceInstUsesWith(EV, Constant::getNullValue(EV.getType()));
+
+ if (isa<ConstantArray>(C) || isa<ConstantStruct>(C)) {
+ // Extract the element indexed by the first index out of the constant
+ Value *V = C->getOperand(*EV.idx_begin());
+ if (EV.getNumIndices() > 1)
+ // Extract the remaining indices out of the constant indexed by the
+ // first index
+ return ExtractValueInst::Create(V, EV.idx_begin() + 1, EV.idx_end());
+ else
+ return ReplaceInstUsesWith(EV, V);
+ }
+ return 0; // Can't handle other constants
+ }
+ if (InsertValueInst *IV = dyn_cast<InsertValueInst>(Agg)) {
+ // We're extracting from an insertvalue instruction, compare the indices
+ const unsigned *exti, *exte, *insi, *inse;
+ for (exti = EV.idx_begin(), insi = IV->idx_begin(),
+ exte = EV.idx_end(), inse = IV->idx_end();
+ exti != exte && insi != inse;
+ ++exti, ++insi) {
+ if (*insi != *exti)
+ // The insert and extract both reference distinctly different elements.
+ // This means the extract is not influenced by the insert, and we can
+ // replace the aggregate operand of the extract with the aggregate
+ // operand of the insert. i.e., replace
+ // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
+ // %E = extractvalue { i32, { i32 } } %I, 0
+ // with
+ // %E = extractvalue { i32, { i32 } } %A, 0
+ return ExtractValueInst::Create(IV->getAggregateOperand(),
+ EV.idx_begin(), EV.idx_end());
+ }
+ if (exti == exte && insi == inse)
+ // Both iterators are at the end: Index lists are identical. Replace
+ // %B = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
+ // %C = extractvalue { i32, { i32 } } %B, 1, 0
+ // with "i32 42"
+ return ReplaceInstUsesWith(EV, IV->getInsertedValueOperand());
+ if (exti == exte) {
+ // The extract list is a prefix of the insert list. i.e. replace
+ // %I = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
+ // %E = extractvalue { i32, { i32 } } %I, 1
+ // with
+ // %X = extractvalue { i32, { i32 } } %A, 1
+ // %E = insertvalue { i32 } %X, i32 42, 0
+ // by switching the order of the insert and extract (though the
+ // insertvalue should be left in, since it may have other uses).
+ Value *NewEV = Builder->CreateExtractValue(IV->getAggregateOperand(),
+ EV.idx_begin(), EV.idx_end());
+ return InsertValueInst::Create(NewEV, IV->getInsertedValueOperand(),
+ insi, inse);
+ }
+ if (insi == inse)
+ // The insert list is a prefix of the extract list
+ // We can simply remove the common indices from the extract and make it
+ // operate on the inserted value instead of the insertvalue result.
+ // i.e., replace
+ // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
+ // %E = extractvalue { i32, { i32 } } %I, 1, 0
+ // with
+ // %E extractvalue { i32 } { i32 42 }, 0
+ return ExtractValueInst::Create(IV->getInsertedValueOperand(),
+ exti, exte);
+ }
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Agg)) {
+ // We're extracting from an intrinsic, see if we're the only user, which
+ // allows us to simplify multiple result intrinsics to simpler things that
+ // just get one value..
+ if (II->hasOneUse()) {
+ // Check if we're grabbing the overflow bit or the result of a 'with
+ // overflow' intrinsic. If it's the latter we can remove the intrinsic
+ // and replace it with a traditional binary instruction.
+ switch (II->getIntrinsicID()) {
+ case Intrinsic::uadd_with_overflow:
+ case Intrinsic::sadd_with_overflow:
+ if (*EV.idx_begin() == 0) { // Normal result.
+ Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
+ II->replaceAllUsesWith(UndefValue::get(II->getType()));
+ EraseInstFromFunction(*II);
+ return BinaryOperator::CreateAdd(LHS, RHS);
+ }
+ break;
+ case Intrinsic::usub_with_overflow:
+ case Intrinsic::ssub_with_overflow:
+ if (*EV.idx_begin() == 0) { // Normal result.
+ Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
+ II->replaceAllUsesWith(UndefValue::get(II->getType()));
+ EraseInstFromFunction(*II);
+ return BinaryOperator::CreateSub(LHS, RHS);
+ }
+ break;
+ case Intrinsic::umul_with_overflow:
+ case Intrinsic::smul_with_overflow:
+ if (*EV.idx_begin() == 0) { // Normal result.
+ Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
+ II->replaceAllUsesWith(UndefValue::get(II->getType()));
+ EraseInstFromFunction(*II);
+ return BinaryOperator::CreateMul(LHS, RHS);
+ }
+ break;
+ default:
+ break;
+ }
+ }
+ }
+ // Can't simplify extracts from other values. Note that nested extracts are
+ // already simplified implicitely by the above (extract ( extract (insert) )
+ // will be translated into extract ( insert ( extract ) ) first and then just
+ // the value inserted, if appropriate).
+ return 0;
+}
+
+/// CheapToScalarize - Return true if the value is cheaper to scalarize than it
+/// is to leave as a vector operation.
+static bool CheapToScalarize(Value *V, bool isConstant) {
+ if (isa<ConstantAggregateZero>(V))
+ return true;
+ if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
+ if (isConstant) return true;
+ // If all elts are the same, we can extract.
+ Constant *Op0 = C->getOperand(0);
+ for (unsigned i = 1; i < C->getNumOperands(); ++i)
+ if (C->getOperand(i) != Op0)
+ return false;
+ return true;
+ }
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) return false;
+
+ // Insert element gets simplified to the inserted element or is deleted if
+ // this is constant idx extract element and its a constant idx insertelt.
+ if (I->getOpcode() == Instruction::InsertElement && isConstant &&
+ isa<ConstantInt>(I->getOperand(2)))
+ return true;
+ if (I->getOpcode() == Instruction::Load && I->hasOneUse())
+ return true;
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
+ if (BO->hasOneUse() &&
+ (CheapToScalarize(BO->getOperand(0), isConstant) ||
+ CheapToScalarize(BO->getOperand(1), isConstant)))
+ return true;
+ if (CmpInst *CI = dyn_cast<CmpInst>(I))
+ if (CI->hasOneUse() &&
+ (CheapToScalarize(CI->getOperand(0), isConstant) ||
+ CheapToScalarize(CI->getOperand(1), isConstant)))
+ return true;
+
+ return false;
+}
+
+/// Read and decode a shufflevector mask.
+///
+/// It turns undef elements into values that are larger than the number of
+/// elements in the input.
+static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) {
+ unsigned NElts = SVI->getType()->getNumElements();
+ if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
+ return std::vector<unsigned>(NElts, 0);
+ if (isa<UndefValue>(SVI->getOperand(2)))
+ return std::vector<unsigned>(NElts, 2*NElts);
+
+ std::vector<unsigned> Result;
+ const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
+ for (User::const_op_iterator i = CP->op_begin(), e = CP->op_end(); i!=e; ++i)
+ if (isa<UndefValue>(*i))
+ Result.push_back(NElts*2); // undef -> 8
+ else
+ Result.push_back(cast<ConstantInt>(*i)->getZExtValue());
+ return Result;
+}
+
+/// FindScalarElement - Given a vector and an element number, see if the scalar
+/// value is already around as a register, for example if it were inserted then
+/// extracted from the vector.
+static Value *FindScalarElement(Value *V, unsigned EltNo,
+ LLVMContext *Context) {
+ assert(isa<VectorType>(V->getType()) && "Not looking at a vector?");
+ const VectorType *PTy = cast<VectorType>(V->getType());
+ unsigned Width = PTy->getNumElements();
+ if (EltNo >= Width) // Out of range access.
+ return UndefValue::get(PTy->getElementType());
+
+ if (isa<UndefValue>(V))
+ return UndefValue::get(PTy->getElementType());
+ else if (isa<ConstantAggregateZero>(V))
+ return Constant::getNullValue(PTy->getElementType());
+ else if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
+ return CP->getOperand(EltNo);
+ else if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
+ // If this is an insert to a variable element, we don't know what it is.
+ if (!isa<ConstantInt>(III->getOperand(2)))
+ return 0;
+ unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
+
+ // If this is an insert to the element we are looking for, return the
+ // inserted value.
+ if (EltNo == IIElt)
+ return III->getOperand(1);
+
+ // Otherwise, the insertelement doesn't modify the value, recurse on its
+ // vector input.
+ return FindScalarElement(III->getOperand(0), EltNo, Context);
+ } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
+ unsigned LHSWidth =
+ cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
+ unsigned InEl = getShuffleMask(SVI)[EltNo];
+ if (InEl < LHSWidth)
+ return FindScalarElement(SVI->getOperand(0), InEl, Context);
+ else if (InEl < LHSWidth*2)
+ return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth, Context);
+ else
+ return UndefValue::get(PTy->getElementType());
+ }
+
+ // Otherwise, we don't know.
+ return 0;
+}
+
+Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
+ // If vector val is undef, replace extract with scalar undef.
+ if (isa<UndefValue>(EI.getOperand(0)))
+ return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
+
+ // If vector val is constant 0, replace extract with scalar 0.
+ if (isa<ConstantAggregateZero>(EI.getOperand(0)))
+ return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
+
+ if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
+ // If vector val is constant with all elements the same, replace EI with
+ // that element. When the elements are not identical, we cannot replace yet
+ // (we do that below, but only when the index is constant).
+ Constant *op0 = C->getOperand(0);
+ for (unsigned i = 1; i != C->getNumOperands(); ++i)
+ if (C->getOperand(i) != op0) {
+ op0 = 0;
+ break;
+ }
+ if (op0)
+ return ReplaceInstUsesWith(EI, op0);
+ }
+
+ // If extracting a specified index from the vector, see if we can recursively
+ // find a previously computed scalar that was inserted into the vector.
+ if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
+ unsigned IndexVal = IdxC->getZExtValue();
+ unsigned VectorWidth = EI.getVectorOperandType()->getNumElements();
+
+ // If this is extracting an invalid index, turn this into undef, to avoid
+ // crashing the code below.
+ if (IndexVal >= VectorWidth)
+ return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
+
+ // This instruction only demands the single element from the input vector.
+ // If the input vector has a single use, simplify it based on this use
+ // property.
+ if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
+ APInt UndefElts(VectorWidth, 0);
+ APInt DemandedMask(VectorWidth, 1 << IndexVal);
+ if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
+ DemandedMask, UndefElts)) {
+ EI.setOperand(0, V);
+ return &EI;
+ }
+ }
+
+ if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal, Context))
+ return ReplaceInstUsesWith(EI, Elt);
+
+ // If the this extractelement is directly using a bitcast from a vector of
+ // the same number of elements, see if we can find the source element from
+ // it. In this case, we will end up needing to bitcast the scalars.
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
+ if (const VectorType *VT =
+ dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
+ if (VT->getNumElements() == VectorWidth)
+ if (Value *Elt = FindScalarElement(BCI->getOperand(0),
+ IndexVal, Context))
+ return new BitCastInst(Elt, EI.getType());
+ }
+ }
+
+ if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
+ // Push extractelement into predecessor operation if legal and
+ // profitable to do so
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
+ if (I->hasOneUse() &&
+ CheapToScalarize(BO, isa<ConstantInt>(EI.getOperand(1)))) {
+ Value *newEI0 =
+ Builder->CreateExtractElement(BO->getOperand(0), EI.getOperand(1),
+ EI.getName()+".lhs");
+ Value *newEI1 =
+ Builder->CreateExtractElement(BO->getOperand(1), EI.getOperand(1),
+ EI.getName()+".rhs");
+ return BinaryOperator::Create(BO->getOpcode(), newEI0, newEI1);
+ }
+ } else if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
+ // Extracting the inserted element?
+ if (IE->getOperand(2) == EI.getOperand(1))
+ return ReplaceInstUsesWith(EI, IE->getOperand(1));
+ // If the inserted and extracted elements are constants, they must not
+ // be the same value, extract from the pre-inserted value instead.
+ if (isa<Constant>(IE->getOperand(2)) && isa<Constant>(EI.getOperand(1))) {
+ Worklist.AddValue(EI.getOperand(0));
+ EI.setOperand(0, IE->getOperand(0));
+ return &EI;
+ }
+ } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) {
+ // If this is extracting an element from a shufflevector, figure out where
+ // it came from and extract from the appropriate input element instead.
+ if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
+ unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
+ Value *Src;
+ unsigned LHSWidth =
+ cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
+
+ if (SrcIdx < LHSWidth)
+ Src = SVI->getOperand(0);
+ else if (SrcIdx < LHSWidth*2) {
+ SrcIdx -= LHSWidth;
+ Src = SVI->getOperand(1);
+ } else {
+ return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
+ }
+ return ExtractElementInst::Create(Src,
+ ConstantInt::get(Type::getInt32Ty(*Context), SrcIdx,
+ false));
+ }
+ }
+ // FIXME: Canonicalize extractelement(bitcast) -> bitcast(extractelement)
+ }
+ return 0;
+}
+
+/// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
+/// elements from either LHS or RHS, return the shuffle mask and true.
+/// Otherwise, return false.
+static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
+ std::vector<Constant*> &Mask,
+ LLVMContext *Context) {
+ assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
+ "Invalid CollectSingleShuffleElements");
+ unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
+
+ if (isa<UndefValue>(V)) {
+ Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(*Context)));
+ return true;
+ } else if (V == LHS) {
+ for (unsigned i = 0; i != NumElts; ++i)
+ Mask.push_back(ConstantInt::get(Type::getInt32Ty(*Context), i));
+ return true;
+ } else if (V == RHS) {
+ for (unsigned i = 0; i != NumElts; ++i)
+ Mask.push_back(ConstantInt::get(Type::getInt32Ty(*Context), i+NumElts));
+ return true;
+ } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
+ // If this is an insert of an extract from some other vector, include it.
+ Value *VecOp = IEI->getOperand(0);
+ Value *ScalarOp = IEI->getOperand(1);
+ Value *IdxOp = IEI->getOperand(2);
+
+ if (!isa<ConstantInt>(IdxOp))
+ return false;
+ unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
+
+ if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
+ // Okay, we can handle this if the vector we are insertinting into is
+ // transitively ok.
+ if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask, Context)) {
+ // If so, update the mask to reflect the inserted undef.
+ Mask[InsertedIdx] = UndefValue::get(Type::getInt32Ty(*Context));
+ return true;
+ }
+ } else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
+ if (isa<ConstantInt>(EI->getOperand(1)) &&
+ EI->getOperand(0)->getType() == V->getType()) {
+ unsigned ExtractedIdx =
+ cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
+
+ // This must be extracting from either LHS or RHS.
+ if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
+ // Okay, we can handle this if the vector we are insertinting into is
+ // transitively ok.
+ if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask, Context)) {
+ // If so, update the mask to reflect the inserted value.
+ if (EI->getOperand(0) == LHS) {
+ Mask[InsertedIdx % NumElts] =
+ ConstantInt::get(Type::getInt32Ty(*Context), ExtractedIdx);
+ } else {
+ assert(EI->getOperand(0) == RHS);
+ Mask[InsertedIdx % NumElts] =
+ ConstantInt::get(Type::getInt32Ty(*Context), ExtractedIdx+NumElts);
+
+ }
+ return true;
+ }
+ }
+ }
+ }
+ }
+ // TODO: Handle shufflevector here!
+
+ return false;
+}
+
+/// CollectShuffleElements - We are building a shuffle of V, using RHS as the
+/// RHS of the shuffle instruction, if it is not null. Return a shuffle mask
+/// that computes V and the LHS value of the shuffle.
+static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
+ Value *&RHS, LLVMContext *Context) {
+ assert(isa<VectorType>(V->getType()) &&
+ (RHS == 0 || V->getType() == RHS->getType()) &&
+ "Invalid shuffle!");
+ unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
+
+ if (isa<UndefValue>(V)) {
+ Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(*Context)));
+ return V;
+ } else if (isa<ConstantAggregateZero>(V)) {
+ Mask.assign(NumElts, ConstantInt::get(Type::getInt32Ty(*Context), 0));
+ return V;
+ } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
+ // If this is an insert of an extract from some other vector, include it.
+ Value *VecOp = IEI->getOperand(0);
+ Value *ScalarOp = IEI->getOperand(1);
+ Value *IdxOp = IEI->getOperand(2);
+
+ if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
+ if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
+ EI->getOperand(0)->getType() == V->getType()) {
+ unsigned ExtractedIdx =
+ cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
+ unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
+
+ // Either the extracted from or inserted into vector must be RHSVec,
+ // otherwise we'd end up with a shuffle of three inputs.
+ if (EI->getOperand(0) == RHS || RHS == 0) {
+ RHS = EI->getOperand(0);
+ Value *V = CollectShuffleElements(VecOp, Mask, RHS, Context);
+ Mask[InsertedIdx % NumElts] =
+ ConstantInt::get(Type::getInt32Ty(*Context), NumElts+ExtractedIdx);
+ return V;
+ }
+
+ if (VecOp == RHS) {
+ Value *V = CollectShuffleElements(EI->getOperand(0), Mask,
+ RHS, Context);
+ // Everything but the extracted element is replaced with the RHS.
+ for (unsigned i = 0; i != NumElts; ++i) {
+ if (i != InsertedIdx)
+ Mask[i] = ConstantInt::get(Type::getInt32Ty(*Context), NumElts+i);
+ }
+ return V;
+ }
+
+ // If this insertelement is a chain that comes from exactly these two
+ // vectors, return the vector and the effective shuffle.
+ if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask,
+ Context))
+ return EI->getOperand(0);
+
+ }
+ }
+ }
+ // TODO: Handle shufflevector here!
+
+ // Otherwise, can't do anything fancy. Return an identity vector.
+ for (unsigned i = 0; i != NumElts; ++i)
+ Mask.push_back(ConstantInt::get(Type::getInt32Ty(*Context), i));
+ return V;
+}
+
+Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
+ Value *VecOp = IE.getOperand(0);
+ Value *ScalarOp = IE.getOperand(1);
+ Value *IdxOp = IE.getOperand(2);
+
+ // Inserting an undef or into an undefined place, remove this.
+ if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
+ ReplaceInstUsesWith(IE, VecOp);
+
+ // If the inserted element was extracted from some other vector, and if the
+ // indexes are constant, try to turn this into a shufflevector operation.
+ if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
+ if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
+ EI->getOperand(0)->getType() == IE.getType()) {
+ unsigned NumVectorElts = IE.getType()->getNumElements();
+ unsigned ExtractedIdx =
+ cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
+ unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
+
+ if (ExtractedIdx >= NumVectorElts) // Out of range extract.
+ return ReplaceInstUsesWith(IE, VecOp);
+
+ if (InsertedIdx >= NumVectorElts) // Out of range insert.
+ return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
+
+ // If we are extracting a value from a vector, then inserting it right
+ // back into the same place, just use the input vector.
+ if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
+ return ReplaceInstUsesWith(IE, VecOp);
+
+ // If this insertelement isn't used by some other insertelement, turn it
+ // (and any insertelements it points to), into one big shuffle.
+ if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
+ std::vector<Constant*> Mask;
+ Value *RHS = 0;
+ Value *LHS = CollectShuffleElements(&IE, Mask, RHS, Context);
+ if (RHS == 0) RHS = UndefValue::get(LHS->getType());
+ // We now have a shuffle of LHS, RHS, Mask.
+ return new ShuffleVectorInst(LHS, RHS,
+ ConstantVector::get(Mask));
+ }
+ }
+ }
+
+ unsigned VWidth = cast<VectorType>(VecOp->getType())->getNumElements();
+ APInt UndefElts(VWidth, 0);
+ APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
+ if (SimplifyDemandedVectorElts(&IE, AllOnesEltMask, UndefElts))
+ return &IE;
+
+ return 0;
+}
+
+
+Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
+ Value *LHS = SVI.getOperand(0);
+ Value *RHS = SVI.getOperand(1);
+ std::vector<unsigned> Mask = getShuffleMask(&SVI);
+
+ bool MadeChange = false;
+
+ // Undefined shuffle mask -> undefined value.
+ if (isa<UndefValue>(SVI.getOperand(2)))
+ return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
+
+ unsigned VWidth = cast<VectorType>(SVI.getType())->getNumElements();
+
+ if (VWidth != cast<VectorType>(LHS->getType())->getNumElements())
+ return 0;
+
+ APInt UndefElts(VWidth, 0);
+ APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
+ if (SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
+ LHS = SVI.getOperand(0);
+ RHS = SVI.getOperand(1);
+ MadeChange = true;
+ }
+
+ // Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
+ // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
+ if (LHS == RHS || isa<UndefValue>(LHS)) {
+ if (isa<UndefValue>(LHS) && LHS == RHS) {
+ // shuffle(undef,undef,mask) -> undef.
+ return ReplaceInstUsesWith(SVI, LHS);
+ }
+
+ // Remap any references to RHS to use LHS.
+ std::vector<Constant*> Elts;
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+ if (Mask[i] >= 2*e)
+ Elts.push_back(UndefValue::get(Type::getInt32Ty(*Context)));
+ else {
+ if ((Mask[i] >= e && isa<UndefValue>(RHS)) ||
+ (Mask[i] < e && isa<UndefValue>(LHS))) {
+ Mask[i] = 2*e; // Turn into undef.
+ Elts.push_back(UndefValue::get(Type::getInt32Ty(*Context)));
+ } else {
+ Mask[i] = Mask[i] % e; // Force to LHS.
+ Elts.push_back(ConstantInt::get(Type::getInt32Ty(*Context), Mask[i]));
+ }
+ }
+ }
+ SVI.setOperand(0, SVI.getOperand(1));
+ SVI.setOperand(1, UndefValue::get(RHS->getType()));
+ SVI.setOperand(2, ConstantVector::get(Elts));
+ LHS = SVI.getOperand(0);
+ RHS = SVI.getOperand(1);
+ MadeChange = true;
+ }
+
+ // Analyze the shuffle, are the LHS or RHS and identity shuffles?
+ bool isLHSID = true, isRHSID = true;
+
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+ if (Mask[i] >= e*2) continue; // Ignore undef values.
+ // Is this an identity shuffle of the LHS value?
+ isLHSID &= (Mask[i] == i);
+
+ // Is this an identity shuffle of the RHS value?
+ isRHSID &= (Mask[i]-e == i);
+ }
+
+ // Eliminate identity shuffles.
+ if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
+ if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
+
+ // If the LHS is a shufflevector itself, see if we can combine it with this
+ // one without producing an unusual shuffle. Here we are really conservative:
+ // we are absolutely afraid of producing a shuffle mask not in the input
+ // program, because the code gen may not be smart enough to turn a merged
+ // shuffle into two specific shuffles: it may produce worse code. As such,
+ // we only merge two shuffles if the result is one of the two input shuffle
+ // masks. In this case, merging the shuffles just removes one instruction,
+ // which we know is safe. This is good for things like turning:
+ // (splat(splat)) -> splat.
+ if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
+ if (isa<UndefValue>(RHS)) {
+ std::vector<unsigned> LHSMask = getShuffleMask(LHSSVI);
+
+ if (LHSMask.size() == Mask.size()) {
+ std::vector<unsigned> NewMask;
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i)
+ if (Mask[i] >= e)
+ NewMask.push_back(2*e);
+ else
+ NewMask.push_back(LHSMask[Mask[i]]);
+
+ // If the result mask is equal to the src shuffle or this
+ // shuffle mask, do the replacement.
+ if (NewMask == LHSMask || NewMask == Mask) {
+ unsigned LHSInNElts =
+ cast<VectorType>(LHSSVI->getOperand(0)->getType())->
+ getNumElements();
+ std::vector<Constant*> Elts;
+ for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
+ if (NewMask[i] >= LHSInNElts*2) {
+ Elts.push_back(UndefValue::get(Type::getInt32Ty(*Context)));
+ } else {
+ Elts.push_back(ConstantInt::get(Type::getInt32Ty(*Context),
+ NewMask[i]));
+ }
+ }
+ return new ShuffleVectorInst(LHSSVI->getOperand(0),
+ LHSSVI->getOperand(1),
+ ConstantVector::get(Elts));
+ }
+ }
+ }
+ }
+
+ return MadeChange ? &SVI : 0;
+}
+
+
+
+
+/// TryToSinkInstruction - Try to move the specified instruction from its
+/// current block into the beginning of DestBlock, which can only happen if it's
+/// safe to move the instruction past all of the instructions between it and the
+/// end of its block.
+static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
+ assert(I->hasOneUse() && "Invariants didn't hold!");
+
+ // Cannot move control-flow-involving, volatile loads, vaarg, etc.
+ if (isa<PHINode>(I) || I->mayHaveSideEffects() || isa<TerminatorInst>(I))
+ return false;
+
+ // Do not sink alloca instructions out of the entry block.
+ if (isa<AllocaInst>(I) && I->getParent() ==
+ &DestBlock->getParent()->getEntryBlock())
+ return false;
+
+ // We can only sink load instructions if there is nothing between the load and
+ // the end of block that could change the value.
+ if (I->mayReadFromMemory()) {
+ for (BasicBlock::iterator Scan = I, E = I->getParent()->end();
+ Scan != E; ++Scan)
+ if (Scan->mayWriteToMemory())
+ return false;
+ }
+
+ BasicBlock::iterator InsertPos = DestBlock->getFirstNonPHI();
+
+ CopyPrecedingStopPoint(I, InsertPos);
+ I->moveBefore(InsertPos);
+ ++NumSunkInst;
+ return true;
+}
+
+
+/// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
+/// all reachable code to the worklist.
+///
+/// This has a couple of tricks to make the code faster and more powerful. In
+/// particular, we constant fold and DCE instructions as we go, to avoid adding
+/// them to the worklist (this significantly speeds up instcombine on code where
+/// many instructions are dead or constant). Additionally, if we find a branch
+/// whose condition is a known constant, we only visit the reachable successors.
+///
+static bool AddReachableCodeToWorklist(BasicBlock *BB,
+ SmallPtrSet<BasicBlock*, 64> &Visited,
+ InstCombiner &IC,
+ const TargetData *TD) {
+ bool MadeIRChange = false;
+ SmallVector<BasicBlock*, 256> Worklist;
+ Worklist.push_back(BB);
+
+ std::vector<Instruction*> InstrsForInstCombineWorklist;
+ InstrsForInstCombineWorklist.reserve(128);
+
+ SmallPtrSet<ConstantExpr*, 64> FoldedConstants;
+
+ while (!Worklist.empty()) {
+ BB = Worklist.back();
+ Worklist.pop_back();
+
+ // We have now visited this block! If we've already been here, ignore it.
+ if (!Visited.insert(BB)) continue;
+
+ for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
+ Instruction *Inst = BBI++;
+
+ // DCE instruction if trivially dead.
+ if (isInstructionTriviallyDead(Inst)) {
+ ++NumDeadInst;
+ DEBUG(errs() << "IC: DCE: " << *Inst << '\n');
+ Inst->eraseFromParent();
+ continue;
+ }
+
+ // ConstantProp instruction if trivially constant.
+ if (!Inst->use_empty() && isa<Constant>(Inst->getOperand(0)))
+ if (Constant *C = ConstantFoldInstruction(Inst, TD)) {
+ DEBUG(errs() << "IC: ConstFold to: " << *C << " from: "
+ << *Inst << '\n');
+ Inst->replaceAllUsesWith(C);
+ ++NumConstProp;
+ Inst->eraseFromParent();
+ continue;
+ }
+
+
+
+ if (TD) {
+ // See if we can constant fold its operands.
+ for (User::op_iterator i = Inst->op_begin(), e = Inst->op_end();
+ i != e; ++i) {
+ ConstantExpr *CE = dyn_cast<ConstantExpr>(i);
+ if (CE == 0) continue;
+
+ // If we already folded this constant, don't try again.
+ if (!FoldedConstants.insert(CE))
+ continue;
+
+ Constant *NewC = ConstantFoldConstantExpression(CE, TD);
+ if (NewC && NewC != CE) {
+ *i = NewC;
+ MadeIRChange = true;
+ }
+ }
+ }
+
+
+ InstrsForInstCombineWorklist.push_back(Inst);
+ }
+
+ // Recursively visit successors. If this is a branch or switch on a
+ // constant, only visit the reachable successor.
+ TerminatorInst *TI = BB->getTerminator();
+ if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
+ if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
+ bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
+ BasicBlock *ReachableBB = BI->getSuccessor(!CondVal);
+ Worklist.push_back(ReachableBB);
+ continue;
+ }
+ } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
+ if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
+ // See if this is an explicit destination.
+ for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i)
+ if (SI->getCaseValue(i) == Cond) {
+ BasicBlock *ReachableBB = SI->getSuccessor(i);
+ Worklist.push_back(ReachableBB);
+ continue;
+ }
+
+ // Otherwise it is the default destination.
+ Worklist.push_back(SI->getSuccessor(0));
+ continue;
+ }
+ }
+
+ for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
+ Worklist.push_back(TI->getSuccessor(i));
+ }
+
+ // Once we've found all of the instructions to add to instcombine's worklist,
+ // add them in reverse order. This way instcombine will visit from the top
+ // of the function down. This jives well with the way that it adds all uses
+ // of instructions to the worklist after doing a transformation, thus avoiding
+ // some N^2 behavior in pathological cases.
+ IC.Worklist.AddInitialGroup(&InstrsForInstCombineWorklist[0],
+ InstrsForInstCombineWorklist.size());
+
+ return MadeIRChange;
+}
+
+bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
+ MadeIRChange = false;
+
+ DEBUG(errs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
+ << F.getNameStr() << "\n");
+
+ {
+ // Do a depth-first traversal of the function, populate the worklist with
+ // the reachable instructions. Ignore blocks that are not reachable. Keep
+ // track of which blocks we visit.
+ SmallPtrSet<BasicBlock*, 64> Visited;
+ MadeIRChange |= AddReachableCodeToWorklist(F.begin(), Visited, *this, TD);
+
+ // Do a quick scan over the function. If we find any blocks that are
+ // unreachable, remove any instructions inside of them. This prevents
+ // the instcombine code from having to deal with some bad special cases.
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+ if (!Visited.count(BB)) {
+ Instruction *Term = BB->getTerminator();
+ while (Term != BB->begin()) { // Remove instrs bottom-up
+ BasicBlock::iterator I = Term; --I;
+
+ DEBUG(errs() << "IC: DCE: " << *I << '\n');
+ // A debug intrinsic shouldn't force another iteration if we weren't
+ // going to do one without it.
+ if (!isa<DbgInfoIntrinsic>(I)) {
+ ++NumDeadInst;
+ MadeIRChange = true;
+ }
+
+ // If I is not void type then replaceAllUsesWith undef.
+ // This allows ValueHandlers and custom metadata to adjust itself.
+ if (!I->getType()->isVoidTy())
+ I->replaceAllUsesWith(UndefValue::get(I->getType()));
+ I->eraseFromParent();
+ }
+ }
+ }
+
+ while (!Worklist.isEmpty()) {
+ Instruction *I = Worklist.RemoveOne();
+ if (I == 0) continue; // skip null values.
+
+ // Check to see if we can DCE the instruction.
+ if (isInstructionTriviallyDead(I)) {
+ DEBUG(errs() << "IC: DCE: " << *I << '\n');
+ EraseInstFromFunction(*I);
+ ++NumDeadInst;
+ MadeIRChange = true;
+ continue;
+ }
+
+ // Instruction isn't dead, see if we can constant propagate it.
+ if (!I->use_empty() && isa<Constant>(I->getOperand(0)))
+ if (Constant *C = ConstantFoldInstruction(I, TD)) {
+ DEBUG(errs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
+
+ // Add operands to the worklist.
+ ReplaceInstUsesWith(*I, C);
+ ++NumConstProp;
+ EraseInstFromFunction(*I);
+ MadeIRChange = true;
+ continue;
+ }
+
+ // See if we can trivially sink this instruction to a successor basic block.
+ if (I->hasOneUse()) {
+ BasicBlock *BB = I->getParent();
+ Instruction *UserInst = cast<Instruction>(I->use_back());
+ BasicBlock *UserParent;
+
+ // Get the block the use occurs in.
+ if (PHINode *PN = dyn_cast<PHINode>(UserInst))
+ UserParent = PN->getIncomingBlock(I->use_begin().getUse());
+ else
+ UserParent = UserInst->getParent();
+
+ if (UserParent != BB) {
+ bool UserIsSuccessor = false;
+ // See if the user is one of our successors.
+ for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
+ if (*SI == UserParent) {
+ UserIsSuccessor = true;
+ break;
+ }
+
+ // If the user is one of our immediate successors, and if that successor
+ // only has us as a predecessors (we'd have to split the critical edge
+ // otherwise), we can keep going.
+ if (UserIsSuccessor && UserParent->getSinglePredecessor())
+ // Okay, the CFG is simple enough, try to sink this instruction.
+ MadeIRChange |= TryToSinkInstruction(I, UserParent);
+ }
+ }
+
+ // Now that we have an instruction, try combining it to simplify it.
+ Builder->SetInsertPoint(I->getParent(), I);
+
+#ifndef NDEBUG
+ std::string OrigI;
+#endif
+ DEBUG(raw_string_ostream SS(OrigI); I->print(SS); OrigI = SS.str(););
+ DEBUG(errs() << "IC: Visiting: " << OrigI << '\n');
+
+ if (Instruction *Result = visit(*I)) {
+ ++NumCombined;
+ // Should we replace the old instruction with a new one?
+ if (Result != I) {
+ DEBUG(errs() << "IC: Old = " << *I << '\n'
+ << " New = " << *Result << '\n');
+
+ // Everything uses the new instruction now.
+ I->replaceAllUsesWith(Result);
+
+ // Push the new instruction and any users onto the worklist.
+ Worklist.Add(Result);
+ Worklist.AddUsersToWorkList(*Result);
+
+ // Move the name to the new instruction first.
+ Result->takeName(I);
+
+ // Insert the new instruction into the basic block...
+ BasicBlock *InstParent = I->getParent();
+ BasicBlock::iterator InsertPos = I;
+
+ if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
+ while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
+ ++InsertPos;
+
+ InstParent->getInstList().insert(InsertPos, Result);
+
+ EraseInstFromFunction(*I);
+ } else {
+#ifndef NDEBUG
+ DEBUG(errs() << "IC: Mod = " << OrigI << '\n'
+ << " New = " << *I << '\n');
+#endif
+
+ // If the instruction was modified, it's possible that it is now dead.
+ // if so, remove it.
+ if (isInstructionTriviallyDead(I)) {
+ EraseInstFromFunction(*I);
+ } else {
+ Worklist.Add(I);
+ Worklist.AddUsersToWorkList(*I);
+ }
+ }
+ MadeIRChange = true;
+ }
+ }
+
+ Worklist.Zap();
+ return MadeIRChange;
+}
+
+
+bool InstCombiner::runOnFunction(Function &F) {
+ MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
+ Context = &F.getContext();
+ TD = getAnalysisIfAvailable<TargetData>();
+
+
+ /// Builder - This is an IRBuilder that automatically inserts new
+ /// instructions into the worklist when they are created.
+ IRBuilder<true, TargetFolder, InstCombineIRInserter>
+ TheBuilder(F.getContext(), TargetFolder(TD),
+ InstCombineIRInserter(Worklist));
+ Builder = &TheBuilder;
+
+ bool EverMadeChange = false;
+
+ // Iterate while there is work to do.
+ unsigned Iteration = 0;
+ while (DoOneIteration(F, Iteration++))
+ EverMadeChange = true;
+
+ Builder = 0;
+ return EverMadeChange;
+}
+
+FunctionPass *llvm::createInstructionCombiningPass() {
+ return new InstCombiner();
+}
##===----------------------------------------------------------------------===##
LEVEL = ../..
-PARALLEL_DIRS = Utils Instrumentation Scalar IPO Hello
+PARALLEL_DIRS = Utils Instrumentation Scalar InstCombine IPO Hello
include $(LEVEL)/Makefile.config
GEPSplitter.cpp
GVN.cpp
IndVarSimplify.cpp
- InstructionCombining.cpp
JumpThreading.cpp
LICM.cpp
LoopDeletion.cpp
+++ /dev/null
-//===- InstructionCombining.cpp - Combine multiple instructions -----------===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// InstructionCombining - Combine instructions to form fewer, simple
-// instructions. This pass does not modify the CFG. This pass is where
-// algebraic simplification happens.
-//
-// This pass combines things like:
-// %Y = add i32 %X, 1
-// %Z = add i32 %Y, 1
-// into:
-// %Z = add i32 %X, 2
-//
-// This is a simple worklist driven algorithm.
-//
-// This pass guarantees that the following canonicalizations are performed on
-// the program:
-// 1. If a binary operator has a constant operand, it is moved to the RHS
-// 2. Bitwise operators with constant operands are always grouped so that
-// shifts are performed first, then or's, then and's, then xor's.
-// 3. Compare instructions are converted from <,>,<=,>= to ==,!= if possible
-// 4. All cmp instructions on boolean values are replaced with logical ops
-// 5. add X, X is represented as (X*2) => (X << 1)
-// 6. Multiplies with a power-of-two constant argument are transformed into
-// shifts.
-// ... etc.
-//
-//===----------------------------------------------------------------------===//
-
-#define DEBUG_TYPE "instcombine"
-#include "llvm/Transforms/Scalar.h"
-#include "llvm/IntrinsicInst.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Pass.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/GlobalVariable.h"
-#include "llvm/Operator.h"
-#include "llvm/Analysis/ConstantFolding.h"
-#include "llvm/Analysis/InstructionSimplify.h"
-#include "llvm/Analysis/MemoryBuiltins.h"
-#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Support/CallSite.h"
-#include "llvm/Support/ConstantRange.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/GetElementPtrTypeIterator.h"
-#include "llvm/Support/InstVisitor.h"
-#include "llvm/Support/IRBuilder.h"
-#include "llvm/Support/MathExtras.h"
-#include "llvm/Support/PatternMatch.h"
-#include "llvm/Support/TargetFolder.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/STLExtras.h"
-#include <algorithm>
-#include <climits>
-using namespace llvm;
-using namespace llvm::PatternMatch;
-
-STATISTIC(NumCombined , "Number of insts combined");
-STATISTIC(NumConstProp, "Number of constant folds");
-STATISTIC(NumDeadInst , "Number of dead inst eliminated");
-STATISTIC(NumDeadStore, "Number of dead stores eliminated");
-STATISTIC(NumSunkInst , "Number of instructions sunk");
-
-/// SelectPatternFlavor - We can match a variety of different patterns for
-/// select operations.
-enum SelectPatternFlavor {
- SPF_UNKNOWN = 0,
- SPF_SMIN, SPF_UMIN,
- SPF_SMAX, SPF_UMAX
- //SPF_ABS - TODO.
-};
-
-namespace {
- /// InstCombineWorklist - This is the worklist management logic for
- /// InstCombine.
- class InstCombineWorklist {
- SmallVector<Instruction*, 256> Worklist;
- DenseMap<Instruction*, unsigned> WorklistMap;
-
- void operator=(const InstCombineWorklist&RHS); // DO NOT IMPLEMENT
- InstCombineWorklist(const InstCombineWorklist&); // DO NOT IMPLEMENT
- public:
- InstCombineWorklist() {}
-
- bool isEmpty() const { return Worklist.empty(); }
-
- /// Add - Add the specified instruction to the worklist if it isn't already
- /// in it.
- void Add(Instruction *I) {
- if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second) {
- DEBUG(errs() << "IC: ADD: " << *I << '\n');
- Worklist.push_back(I);
- }
- }
-
- void AddValue(Value *V) {
- if (Instruction *I = dyn_cast<Instruction>(V))
- Add(I);
- }
-
- /// AddInitialGroup - Add the specified batch of stuff in reverse order.
- /// which should only be done when the worklist is empty and when the group
- /// has no duplicates.
- void AddInitialGroup(Instruction *const *List, unsigned NumEntries) {
- assert(Worklist.empty() && "Worklist must be empty to add initial group");
- Worklist.reserve(NumEntries+16);
- DEBUG(errs() << "IC: ADDING: " << NumEntries << " instrs to worklist\n");
- for (; NumEntries; --NumEntries) {
- Instruction *I = List[NumEntries-1];
- WorklistMap.insert(std::make_pair(I, Worklist.size()));
- Worklist.push_back(I);
- }
- }
-
- // Remove - remove I from the worklist if it exists.
- void Remove(Instruction *I) {
- DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
- if (It == WorklistMap.end()) return; // Not in worklist.
-
- // Don't bother moving everything down, just null out the slot.
- Worklist[It->second] = 0;
-
- WorklistMap.erase(It);
- }
-
- Instruction *RemoveOne() {
- Instruction *I = Worklist.back();
- Worklist.pop_back();
- WorklistMap.erase(I);
- return I;
- }
-
- /// AddUsersToWorkList - When an instruction is simplified, add all users of
- /// the instruction to the work lists because they might get more simplified
- /// now.
- ///
- void AddUsersToWorkList(Instruction &I) {
- for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
- UI != UE; ++UI)
- Add(cast<Instruction>(*UI));
- }
-
-
- /// Zap - check that the worklist is empty and nuke the backing store for
- /// the map if it is large.
- void Zap() {
- assert(WorklistMap.empty() && "Worklist empty, but map not?");
-
- // Do an explicit clear, this shrinks the map if needed.
- WorklistMap.clear();
- }
- };
-} // end anonymous namespace.
-
-
-namespace {
- /// InstCombineIRInserter - This is an IRBuilder insertion helper that works
- /// just like the normal insertion helper, but also adds any new instructions
- /// to the instcombine worklist.
- class InstCombineIRInserter : public IRBuilderDefaultInserter<true> {
- InstCombineWorklist &Worklist;
- public:
- InstCombineIRInserter(InstCombineWorklist &WL) : Worklist(WL) {}
-
- void InsertHelper(Instruction *I, const Twine &Name,
- BasicBlock *BB, BasicBlock::iterator InsertPt) const {
- IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt);
- Worklist.Add(I);
- }
- };
-} // end anonymous namespace
-
-
-namespace {
- class InstCombiner : public FunctionPass,
- public InstVisitor<InstCombiner, Instruction*> {
- TargetData *TD;
- bool MustPreserveLCSSA;
- bool MadeIRChange;
- public:
- /// Worklist - All of the instructions that need to be simplified.
- InstCombineWorklist Worklist;
-
- /// Builder - This is an IRBuilder that automatically inserts new
- /// instructions into the worklist when they are created.
- typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy;
- BuilderTy *Builder;
-
- static char ID; // Pass identification, replacement for typeid
- InstCombiner() : FunctionPass(&ID), TD(0), Builder(0) {}
-
- LLVMContext *Context;
- LLVMContext *getContext() const { return Context; }
-
- public:
- virtual bool runOnFunction(Function &F);
-
- bool DoOneIteration(Function &F, unsigned ItNum);
-
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addPreservedID(LCSSAID);
- AU.setPreservesCFG();
- }
-
- TargetData *getTargetData() const { return TD; }
-
- // Visitation implementation - Implement instruction combining for different
- // instruction types. The semantics are as follows:
- // Return Value:
- // null - No change was made
- // I - Change was made, I is still valid, I may be dead though
- // otherwise - Change was made, replace I with returned instruction
- //
- Instruction *visitAdd(BinaryOperator &I);
- Instruction *visitFAdd(BinaryOperator &I);
- Value *OptimizePointerDifference(Value *LHS, Value *RHS, const Type *Ty);
- Instruction *visitSub(BinaryOperator &I);
- Instruction *visitFSub(BinaryOperator &I);
- Instruction *visitMul(BinaryOperator &I);
- Instruction *visitFMul(BinaryOperator &I);
- Instruction *visitURem(BinaryOperator &I);
- Instruction *visitSRem(BinaryOperator &I);
- Instruction *visitFRem(BinaryOperator &I);
- bool SimplifyDivRemOfSelect(BinaryOperator &I);
- Instruction *commonRemTransforms(BinaryOperator &I);
- Instruction *commonIRemTransforms(BinaryOperator &I);
- Instruction *commonDivTransforms(BinaryOperator &I);
- Instruction *commonIDivTransforms(BinaryOperator &I);
- Instruction *visitUDiv(BinaryOperator &I);
- Instruction *visitSDiv(BinaryOperator &I);
- Instruction *visitFDiv(BinaryOperator &I);
- Instruction *FoldAndOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
- Instruction *FoldAndOfFCmps(Instruction &I, FCmpInst *LHS, FCmpInst *RHS);
- Instruction *visitAnd(BinaryOperator &I);
- Instruction *FoldOrOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
- Instruction *FoldOrOfFCmps(Instruction &I, FCmpInst *LHS, FCmpInst *RHS);
- Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op,
- Value *A, Value *B, Value *C);
- Instruction *visitOr (BinaryOperator &I);
- Instruction *visitXor(BinaryOperator &I);
- Instruction *visitShl(BinaryOperator &I);
- Instruction *visitAShr(BinaryOperator &I);
- Instruction *visitLShr(BinaryOperator &I);
- Instruction *commonShiftTransforms(BinaryOperator &I);
- Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI,
- Constant *RHSC);
- Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
- GlobalVariable *GV, CmpInst &ICI,
- ConstantInt *AndCst = 0);
- Instruction *visitFCmpInst(FCmpInst &I);
- Instruction *visitICmpInst(ICmpInst &I);
- Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
- Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
- Instruction *LHS,
- ConstantInt *RHS);
- Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
- ConstantInt *DivRHS);
- Instruction *FoldICmpAddOpCst(ICmpInst &ICI, Value *X, ConstantInt *CI,
- ICmpInst::Predicate Pred, Value *TheAdd);
- Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
- ICmpInst::Predicate Cond, Instruction &I);
- Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
- BinaryOperator &I);
- Instruction *commonCastTransforms(CastInst &CI);
- Instruction *commonIntCastTransforms(CastInst &CI);
- Instruction *commonPointerCastTransforms(CastInst &CI);
- Instruction *visitTrunc(TruncInst &CI);
- Instruction *visitZExt(ZExtInst &CI);
- Instruction *visitSExt(SExtInst &CI);
- Instruction *visitFPTrunc(FPTruncInst &CI);
- Instruction *visitFPExt(CastInst &CI);
- Instruction *visitFPToUI(FPToUIInst &FI);
- Instruction *visitFPToSI(FPToSIInst &FI);
- Instruction *visitUIToFP(CastInst &CI);
- Instruction *visitSIToFP(CastInst &CI);
- Instruction *visitPtrToInt(PtrToIntInst &CI);
- Instruction *visitIntToPtr(IntToPtrInst &CI);
- Instruction *visitBitCast(BitCastInst &CI);
- Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
- Instruction *FI);
- Instruction *FoldSelectIntoOp(SelectInst &SI, Value*, Value*);
- Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
- Value *A, Value *B, Instruction &Outer,
- SelectPatternFlavor SPF2, Value *C);
- Instruction *visitSelectInst(SelectInst &SI);
- Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
- Instruction *visitCallInst(CallInst &CI);
- Instruction *visitInvokeInst(InvokeInst &II);
-
- Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
- Instruction *visitPHINode(PHINode &PN);
- Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
- Instruction *visitAllocaInst(AllocaInst &AI);
- Instruction *visitFree(Instruction &FI);
- Instruction *visitLoadInst(LoadInst &LI);
- Instruction *visitStoreInst(StoreInst &SI);
- Instruction *visitBranchInst(BranchInst &BI);
- Instruction *visitSwitchInst(SwitchInst &SI);
- Instruction *visitInsertElementInst(InsertElementInst &IE);
- Instruction *visitExtractElementInst(ExtractElementInst &EI);
- Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
- Instruction *visitExtractValueInst(ExtractValueInst &EV);
-
- // visitInstruction - Specify what to return for unhandled instructions...
- Instruction *visitInstruction(Instruction &I) { return 0; }
-
- private:
- Instruction *visitCallSite(CallSite CS);
- bool transformConstExprCastCall(CallSite CS);
- Instruction *transformCallThroughTrampoline(CallSite CS);
- Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
- bool DoXform = true);
- bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS);
- DbgDeclareInst *hasOneUsePlusDeclare(Value *V);
-
-
- public:
- // InsertNewInstBefore - insert an instruction New before instruction Old
- // in the program. Add the new instruction to the worklist.
- //
- Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
- assert(New && New->getParent() == 0 &&
- "New instruction already inserted into a basic block!");
- BasicBlock *BB = Old.getParent();
- BB->getInstList().insert(&Old, New); // Insert inst
- Worklist.Add(New);
- return New;
- }
-
- // ReplaceInstUsesWith - This method is to be used when an instruction is
- // found to be dead, replacable with another preexisting expression. Here
- // we add all uses of I to the worklist, replace all uses of I with the new
- // value, then return I, so that the inst combiner will know that I was
- // modified.
- //
- Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
- Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist.
-
- // If we are replacing the instruction with itself, this must be in a
- // segment of unreachable code, so just clobber the instruction.
- if (&I == V)
- V = UndefValue::get(I.getType());
-
- I.replaceAllUsesWith(V);
- return &I;
- }
-
- // EraseInstFromFunction - When dealing with an instruction that has side
- // effects or produces a void value, we can't rely on DCE to delete the
- // instruction. Instead, visit methods should return the value returned by
- // this function.
- Instruction *EraseInstFromFunction(Instruction &I) {
- DEBUG(errs() << "IC: ERASE " << I << '\n');
-
- assert(I.use_empty() && "Cannot erase instruction that is used!");
- // Make sure that we reprocess all operands now that we reduced their
- // use counts.
- if (I.getNumOperands() < 8) {
- for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
- if (Instruction *Op = dyn_cast<Instruction>(*i))
- Worklist.Add(Op);
- }
- Worklist.Remove(&I);
- I.eraseFromParent();
- MadeIRChange = true;
- return 0; // Don't do anything with FI
- }
-
- void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
- APInt &KnownOne, unsigned Depth = 0) const {
- return llvm::ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth);
- }
-
- bool MaskedValueIsZero(Value *V, const APInt &Mask,
- unsigned Depth = 0) const {
- return llvm::MaskedValueIsZero(V, Mask, TD, Depth);
- }
- unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const {
- return llvm::ComputeNumSignBits(Op, TD, Depth);
- }
-
- private:
-
- /// SimplifyCommutative - This performs a few simplifications for
- /// commutative operators.
- bool SimplifyCommutative(BinaryOperator &I);
-
- /// SimplifyDemandedUseBits - Attempts to replace V with a simpler value
- /// based on the demanded bits.
- Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
- APInt& KnownZero, APInt& KnownOne,
- unsigned Depth);
- bool SimplifyDemandedBits(Use &U, APInt DemandedMask,
- APInt& KnownZero, APInt& KnownOne,
- unsigned Depth=0);
-
- /// SimplifyDemandedInstructionBits - Inst is an integer instruction that
- /// SimplifyDemandedBits knows about. See if the instruction has any
- /// properties that allow us to simplify its operands.
- bool SimplifyDemandedInstructionBits(Instruction &Inst);
-
- Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
- APInt& UndefElts, unsigned Depth = 0);
-
- // FoldOpIntoPhi - Given a binary operator, cast instruction, or select
- // which has a PHI node as operand #0, see if we can fold the instruction
- // into the PHI (which is only possible if all operands to the PHI are
- // constants).
- //
- // If AllowAggressive is true, FoldOpIntoPhi will allow certain transforms
- // that would normally be unprofitable because they strongly encourage jump
- // threading.
- Instruction *FoldOpIntoPhi(Instruction &I, bool AllowAggressive = false);
-
- // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
- // operator and they all are only used by the PHI, PHI together their
- // inputs, and do the operation once, to the result of the PHI.
- Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
- Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
- Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
- Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN);
-
-
- Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
- ConstantInt *AndRHS, BinaryOperator &TheAnd);
-
- Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
- bool isSub, Instruction &I);
- Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
- bool isSigned, bool Inside, Instruction &IB);
- Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI);
- Instruction *MatchBSwap(BinaryOperator &I);
- bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
- Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
- Instruction *SimplifyMemSet(MemSetInst *MI);
-
-
- Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
-
- bool CanEvaluateInDifferentType(Value *V, const Type *Ty,
- unsigned CastOpc, int &NumCastsRemoved);
- unsigned GetOrEnforceKnownAlignment(Value *V,
- unsigned PrefAlign = 0);
-
- };
-} // end anonymous namespace
-
-char InstCombiner::ID = 0;
-static RegisterPass<InstCombiner>
-X("instcombine", "Combine redundant instructions");
-
-// getComplexity: Assign a complexity or rank value to LLVM Values...
-// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
-static unsigned getComplexity(Value *V) {
- if (isa<Instruction>(V)) {
- if (BinaryOperator::isNeg(V) ||
- BinaryOperator::isFNeg(V) ||
- BinaryOperator::isNot(V))
- return 3;
- return 4;
- }
- if (isa<Argument>(V)) return 3;
- return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
-}
-
-// isOnlyUse - Return true if this instruction will be deleted if we stop using
-// it.
-static bool isOnlyUse(Value *V) {
- return V->hasOneUse() || isa<Constant>(V);
-}
-
-// getPromotedType - Return the specified type promoted as it would be to pass
-// though a va_arg area...
-static const Type *getPromotedType(const Type *Ty) {
- if (const IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
- if (ITy->getBitWidth() < 32)
- return Type::getInt32Ty(Ty->getContext());
- }
- return Ty;
-}
-
-/// ShouldChangeType - Return true if it is desirable to convert a computation
-/// from 'From' to 'To'. We don't want to convert from a legal to an illegal
-/// type for example, or from a smaller to a larger illegal type.
-static bool ShouldChangeType(const Type *From, const Type *To,
- const TargetData *TD) {
- assert(isa<IntegerType>(From) && isa<IntegerType>(To));
-
- // If we don't have TD, we don't know if the source/dest are legal.
- if (!TD) return false;
-
- unsigned FromWidth = From->getPrimitiveSizeInBits();
- unsigned ToWidth = To->getPrimitiveSizeInBits();
- bool FromLegal = TD->isLegalInteger(FromWidth);
- bool ToLegal = TD->isLegalInteger(ToWidth);
-
- // If this is a legal integer from type, and the result would be an illegal
- // type, don't do the transformation.
- if (FromLegal && !ToLegal)
- return false;
-
- // Otherwise, if both are illegal, do not increase the size of the result. We
- // do allow things like i160 -> i64, but not i64 -> i160.
- if (!FromLegal && !ToLegal && ToWidth > FromWidth)
- return false;
-
- return true;
-}
-
-/// getBitCastOperand - If the specified operand is a CastInst, a constant
-/// expression bitcast, or a GetElementPtrInst with all zero indices, return the
-/// operand value, otherwise return null.
-static Value *getBitCastOperand(Value *V) {
- if (Operator *O = dyn_cast<Operator>(V)) {
- if (O->getOpcode() == Instruction::BitCast)
- return O->getOperand(0);
- if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
- if (GEP->hasAllZeroIndices())
- return GEP->getPointerOperand();
- }
- return 0;
-}
-
-/// This function is a wrapper around CastInst::isEliminableCastPair. It
-/// simply extracts arguments and returns what that function returns.
-static Instruction::CastOps
-isEliminableCastPair(
- const CastInst *CI, ///< The first cast instruction
- unsigned opcode, ///< The opcode of the second cast instruction
- const Type *DstTy, ///< The target type for the second cast instruction
- TargetData *TD ///< The target data for pointer size
-) {
-
- const Type *SrcTy = CI->getOperand(0)->getType(); // A from above
- const Type *MidTy = CI->getType(); // B from above
-
- // Get the opcodes of the two Cast instructions
- Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
- Instruction::CastOps secondOp = Instruction::CastOps(opcode);
-
- unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
- DstTy,
- TD ? TD->getIntPtrType(CI->getContext()) : 0);
-
- // We don't want to form an inttoptr or ptrtoint that converts to an integer
- // type that differs from the pointer size.
- if ((Res == Instruction::IntToPtr &&
- (!TD || SrcTy != TD->getIntPtrType(CI->getContext()))) ||
- (Res == Instruction::PtrToInt &&
- (!TD || DstTy != TD->getIntPtrType(CI->getContext()))))
- Res = 0;
-
- return Instruction::CastOps(Res);
-}
-
-/// ValueRequiresCast - Return true if the cast from "V to Ty" actually results
-/// in any code being generated. It does not require codegen if V is simple
-/// enough or if the cast can be folded into other casts.
-static bool ValueRequiresCast(Instruction::CastOps opcode, const Value *V,
- const Type *Ty, TargetData *TD) {
- if (V->getType() == Ty || isa<Constant>(V)) return false;
-
- // If this is another cast that can be eliminated, it isn't codegen either.
- if (const CastInst *CI = dyn_cast<CastInst>(V))
- if (isEliminableCastPair(CI, opcode, Ty, TD))
- return false;
- return true;
-}
-
-// SimplifyCommutative - This performs a few simplifications for commutative
-// operators:
-//
-// 1. Order operands such that they are listed from right (least complex) to
-// left (most complex). This puts constants before unary operators before
-// binary operators.
-//
-// 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
-// 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
-//
-bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
- bool Changed = false;
- if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
- Changed = !I.swapOperands();
-
- if (!I.isAssociative()) return Changed;
- Instruction::BinaryOps Opcode = I.getOpcode();
- if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
- if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
- if (isa<Constant>(I.getOperand(1))) {
- Constant *Folded = ConstantExpr::get(I.getOpcode(),
- cast<Constant>(I.getOperand(1)),
- cast<Constant>(Op->getOperand(1)));
- I.setOperand(0, Op->getOperand(0));
- I.setOperand(1, Folded);
- return true;
- } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
- if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
- isOnlyUse(Op) && isOnlyUse(Op1)) {
- Constant *C1 = cast<Constant>(Op->getOperand(1));
- Constant *C2 = cast<Constant>(Op1->getOperand(1));
-
- // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
- Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
- Instruction *New = BinaryOperator::Create(Opcode, Op->getOperand(0),
- Op1->getOperand(0),
- Op1->getName(), &I);
- Worklist.Add(New);
- I.setOperand(0, New);
- I.setOperand(1, Folded);
- return true;
- }
- }
- return Changed;
-}
-
-// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
-// if the LHS is a constant zero (which is the 'negate' form).
-//
-static inline Value *dyn_castNegVal(Value *V) {
- if (BinaryOperator::isNeg(V))
- return BinaryOperator::getNegArgument(V);
-
- // Constants can be considered to be negated values if they can be folded.
- if (ConstantInt *C = dyn_cast<ConstantInt>(V))
- return ConstantExpr::getNeg(C);
-
- if (ConstantVector *C = dyn_cast<ConstantVector>(V))
- if (C->getType()->getElementType()->isInteger())
- return ConstantExpr::getNeg(C);
-
- return 0;
-}
-
-// dyn_castFNegVal - Given a 'fsub' instruction, return the RHS of the
-// instruction if the LHS is a constant negative zero (which is the 'negate'
-// form).
-//
-static inline Value *dyn_castFNegVal(Value *V) {
- if (BinaryOperator::isFNeg(V))
- return BinaryOperator::getFNegArgument(V);
-
- // Constants can be considered to be negated values if they can be folded.
- if (ConstantFP *C = dyn_cast<ConstantFP>(V))
- return ConstantExpr::getFNeg(C);
-
- if (ConstantVector *C = dyn_cast<ConstantVector>(V))
- if (C->getType()->getElementType()->isFloatingPoint())
- return ConstantExpr::getFNeg(C);
-
- return 0;
-}
-
-/// MatchSelectPattern - Pattern match integer [SU]MIN, [SU]MAX, and ABS idioms,
-/// returning the kind and providing the out parameter results if we
-/// successfully match.
-static SelectPatternFlavor
-MatchSelectPattern(Value *V, Value *&LHS, Value *&RHS) {
- SelectInst *SI = dyn_cast<SelectInst>(V);
- if (SI == 0) return SPF_UNKNOWN;
-
- ICmpInst *ICI = dyn_cast<ICmpInst>(SI->getCondition());
- if (ICI == 0) return SPF_UNKNOWN;
-
- LHS = ICI->getOperand(0);
- RHS = ICI->getOperand(1);
-
- // (icmp X, Y) ? X : Y
- if (SI->getTrueValue() == ICI->getOperand(0) &&
- SI->getFalseValue() == ICI->getOperand(1)) {
- switch (ICI->getPredicate()) {
- default: return SPF_UNKNOWN; // Equality.
- case ICmpInst::ICMP_UGT:
- case ICmpInst::ICMP_UGE: return SPF_UMAX;
- case ICmpInst::ICMP_SGT:
- case ICmpInst::ICMP_SGE: return SPF_SMAX;
- case ICmpInst::ICMP_ULT:
- case ICmpInst::ICMP_ULE: return SPF_UMIN;
- case ICmpInst::ICMP_SLT:
- case ICmpInst::ICMP_SLE: return SPF_SMIN;
- }
- }
-
- // (icmp X, Y) ? Y : X
- if (SI->getTrueValue() == ICI->getOperand(1) &&
- SI->getFalseValue() == ICI->getOperand(0)) {
- switch (ICI->getPredicate()) {
- default: return SPF_UNKNOWN; // Equality.
- case ICmpInst::ICMP_UGT:
- case ICmpInst::ICMP_UGE: return SPF_UMIN;
- case ICmpInst::ICMP_SGT:
- case ICmpInst::ICMP_SGE: return SPF_SMIN;
- case ICmpInst::ICMP_ULT:
- case ICmpInst::ICMP_ULE: return SPF_UMAX;
- case ICmpInst::ICMP_SLT:
- case ICmpInst::ICMP_SLE: return SPF_SMAX;
- }
- }
-
- // TODO: (X > 4) ? X : 5 --> (X >= 5) ? X : 5 --> MAX(X, 5)
-
- return SPF_UNKNOWN;
-}
-
-/// isFreeToInvert - Return true if the specified value is free to invert (apply
-/// ~ to). This happens in cases where the ~ can be eliminated.
-static inline bool isFreeToInvert(Value *V) {
- // ~(~(X)) -> X.
- if (BinaryOperator::isNot(V))
- return true;
-
- // Constants can be considered to be not'ed values.
- if (isa<ConstantInt>(V))
- return true;
-
- // Compares can be inverted if they have a single use.
- if (CmpInst *CI = dyn_cast<CmpInst>(V))
- return CI->hasOneUse();
-
- return false;
-}
-
-static inline Value *dyn_castNotVal(Value *V) {
- // If this is not(not(x)) don't return that this is a not: we want the two
- // not's to be folded first.
- if (BinaryOperator::isNot(V)) {
- Value *Operand = BinaryOperator::getNotArgument(V);
- if (!isFreeToInvert(Operand))
- return Operand;
- }
-
- // Constants can be considered to be not'ed values...
- if (ConstantInt *C = dyn_cast<ConstantInt>(V))
- return ConstantInt::get(C->getType(), ~C->getValue());
- return 0;
-}
-
-
-
-// dyn_castFoldableMul - If this value is a multiply that can be folded into
-// other computations (because it has a constant operand), return the
-// non-constant operand of the multiply, and set CST to point to the multiplier.
-// Otherwise, return null.
-//
-static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
- if (V->hasOneUse() && V->getType()->isInteger())
- if (Instruction *I = dyn_cast<Instruction>(V)) {
- if (I->getOpcode() == Instruction::Mul)
- if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
- return I->getOperand(0);
- if (I->getOpcode() == Instruction::Shl)
- if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
- // The multiplier is really 1 << CST.
- uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
- uint32_t CSTVal = CST->getLimitedValue(BitWidth);
- CST = ConstantInt::get(V->getType()->getContext(),
- APInt(BitWidth, 1).shl(CSTVal));
- return I->getOperand(0);
- }
- }
- return 0;
-}
-
-/// AddOne - Add one to a ConstantInt
-static Constant *AddOne(Constant *C) {
- return ConstantExpr::getAdd(C,
- ConstantInt::get(C->getType(), 1));
-}
-/// SubOne - Subtract one from a ConstantInt
-static Constant *SubOne(ConstantInt *C) {
- return ConstantExpr::getSub(C,
- ConstantInt::get(C->getType(), 1));
-}
-/// MultiplyOverflows - True if the multiply can not be expressed in an int
-/// this size.
-static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
- uint32_t W = C1->getBitWidth();
- APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
- if (sign) {
- LHSExt.sext(W * 2);
- RHSExt.sext(W * 2);
- } else {
- LHSExt.zext(W * 2);
- RHSExt.zext(W * 2);
- }
-
- APInt MulExt = LHSExt * RHSExt;
-
- if (!sign)
- return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
-
- APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
- APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
- return MulExt.slt(Min) || MulExt.sgt(Max);
-}
-
-
-/// ShrinkDemandedConstant - Check to see if the specified operand of the
-/// specified instruction is a constant integer. If so, check to see if there
-/// are any bits set in the constant that are not demanded. If so, shrink the
-/// constant and return true.
-static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
- APInt Demanded) {
- assert(I && "No instruction?");
- assert(OpNo < I->getNumOperands() && "Operand index too large");
-
- // If the operand is not a constant integer, nothing to do.
- ConstantInt *OpC = dyn_cast<ConstantInt>(I->getOperand(OpNo));
- if (!OpC) return false;
-
- // If there are no bits set that aren't demanded, nothing to do.
- Demanded.zextOrTrunc(OpC->getValue().getBitWidth());
- if ((~Demanded & OpC->getValue()) == 0)
- return false;
-
- // This instruction is producing bits that are not demanded. Shrink the RHS.
- Demanded &= OpC->getValue();
- I->setOperand(OpNo, ConstantInt::get(OpC->getType(), Demanded));
- return true;
-}
-
-// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
-// set of known zero and one bits, compute the maximum and minimum values that
-// could have the specified known zero and known one bits, returning them in
-// min/max.
-static void ComputeSignedMinMaxValuesFromKnownBits(const APInt& KnownZero,
- const APInt& KnownOne,
- APInt& Min, APInt& Max) {
- assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
- KnownZero.getBitWidth() == Min.getBitWidth() &&
- KnownZero.getBitWidth() == Max.getBitWidth() &&
- "KnownZero, KnownOne and Min, Max must have equal bitwidth.");
- APInt UnknownBits = ~(KnownZero|KnownOne);
-
- // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
- // bit if it is unknown.
- Min = KnownOne;
- Max = KnownOne|UnknownBits;
-
- if (UnknownBits.isNegative()) { // Sign bit is unknown
- Min.set(Min.getBitWidth()-1);
- Max.clear(Max.getBitWidth()-1);
- }
-}
-
-// ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
-// a set of known zero and one bits, compute the maximum and minimum values that
-// could have the specified known zero and known one bits, returning them in
-// min/max.
-static void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero,
- const APInt &KnownOne,
- APInt &Min, APInt &Max) {
- assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
- KnownZero.getBitWidth() == Min.getBitWidth() &&
- KnownZero.getBitWidth() == Max.getBitWidth() &&
- "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
- APInt UnknownBits = ~(KnownZero|KnownOne);
-
- // The minimum value is when the unknown bits are all zeros.
- Min = KnownOne;
- // The maximum value is when the unknown bits are all ones.
- Max = KnownOne|UnknownBits;
-}
-
-/// SimplifyDemandedInstructionBits - Inst is an integer instruction that
-/// SimplifyDemandedBits knows about. See if the instruction has any
-/// properties that allow us to simplify its operands.
-bool InstCombiner::SimplifyDemandedInstructionBits(Instruction &Inst) {
- unsigned BitWidth = Inst.getType()->getScalarSizeInBits();
- APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
- APInt DemandedMask(APInt::getAllOnesValue(BitWidth));
-
- Value *V = SimplifyDemandedUseBits(&Inst, DemandedMask,
- KnownZero, KnownOne, 0);
- if (V == 0) return false;
- if (V == &Inst) return true;
- ReplaceInstUsesWith(Inst, V);
- return true;
-}
-
-/// SimplifyDemandedBits - This form of SimplifyDemandedBits simplifies the
-/// specified instruction operand if possible, updating it in place. It returns
-/// true if it made any change and false otherwise.
-bool InstCombiner::SimplifyDemandedBits(Use &U, APInt DemandedMask,
- APInt &KnownZero, APInt &KnownOne,
- unsigned Depth) {
- Value *NewVal = SimplifyDemandedUseBits(U.get(), DemandedMask,
- KnownZero, KnownOne, Depth);
- if (NewVal == 0) return false;
- U = NewVal;
- return true;
-}
-
-
-/// SimplifyDemandedUseBits - This function attempts to replace V with a simpler
-/// value based on the demanded bits. When this function is called, it is known
-/// that only the bits set in DemandedMask of the result of V are ever used
-/// downstream. Consequently, depending on the mask and V, it may be possible
-/// to replace V with a constant or one of its operands. In such cases, this
-/// function does the replacement and returns true. In all other cases, it
-/// returns false after analyzing the expression and setting KnownOne and known
-/// to be one in the expression. KnownZero contains all the bits that are known
-/// to be zero in the expression. These are provided to potentially allow the
-/// caller (which might recursively be SimplifyDemandedBits itself) to simplify
-/// the expression. KnownOne and KnownZero always follow the invariant that
-/// KnownOne & KnownZero == 0. That is, a bit can't be both 1 and 0. Note that
-/// the bits in KnownOne and KnownZero may only be accurate for those bits set
-/// in DemandedMask. Note also that the bitwidth of V, DemandedMask, KnownZero
-/// and KnownOne must all be the same.
-///
-/// This returns null if it did not change anything and it permits no
-/// simplification. This returns V itself if it did some simplification of V's
-/// operands based on the information about what bits are demanded. This returns
-/// some other non-null value if it found out that V is equal to another value
-/// in the context where the specified bits are demanded, but not for all users.
-Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
- APInt &KnownZero, APInt &KnownOne,
- unsigned Depth) {
- assert(V != 0 && "Null pointer of Value???");
- assert(Depth <= 6 && "Limit Search Depth");
- uint32_t BitWidth = DemandedMask.getBitWidth();
- const Type *VTy = V->getType();
- assert((TD || !isa<PointerType>(VTy)) &&
- "SimplifyDemandedBits needs to know bit widths!");
- assert((!TD || TD->getTypeSizeInBits(VTy->getScalarType()) == BitWidth) &&
- (!VTy->isIntOrIntVector() ||
- VTy->getScalarSizeInBits() == BitWidth) &&
- KnownZero.getBitWidth() == BitWidth &&
- KnownOne.getBitWidth() == BitWidth &&
- "Value *V, DemandedMask, KnownZero and KnownOne "
- "must have same BitWidth");
- if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
- // We know all of the bits for a constant!
- KnownOne = CI->getValue() & DemandedMask;
- KnownZero = ~KnownOne & DemandedMask;
- return 0;
- }
- if (isa<ConstantPointerNull>(V)) {
- // We know all of the bits for a constant!
- KnownOne.clear();
- KnownZero = DemandedMask;
- return 0;
- }
-
- KnownZero.clear();
- KnownOne.clear();
- if (DemandedMask == 0) { // Not demanding any bits from V.
- if (isa<UndefValue>(V))
- return 0;
- return UndefValue::get(VTy);
- }
-
- if (Depth == 6) // Limit search depth.
- return 0;
-
- APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0);
- APInt &RHSKnownZero = KnownZero, &RHSKnownOne = KnownOne;
-
- Instruction *I = dyn_cast<Instruction>(V);
- if (!I) {
- ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
- return 0; // Only analyze instructions.
- }
-
- // If there are multiple uses of this value and we aren't at the root, then
- // we can't do any simplifications of the operands, because DemandedMask
- // only reflects the bits demanded by *one* of the users.
- if (Depth != 0 && !I->hasOneUse()) {
- // Despite the fact that we can't simplify this instruction in all User's
- // context, we can at least compute the knownzero/knownone bits, and we can
- // do simplifications that apply to *just* the one user if we know that
- // this instruction has a simpler value in that context.
- if (I->getOpcode() == Instruction::And) {
- // If either the LHS or the RHS are Zero, the result is zero.
- ComputeMaskedBits(I->getOperand(1), DemandedMask,
- RHSKnownZero, RHSKnownOne, Depth+1);
- ComputeMaskedBits(I->getOperand(0), DemandedMask & ~RHSKnownZero,
- LHSKnownZero, LHSKnownOne, Depth+1);
-
- // If all of the demanded bits are known 1 on one side, return the other.
- // These bits cannot contribute to the result of the 'and' in this
- // context.
- if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) ==
- (DemandedMask & ~LHSKnownZero))
- return I->getOperand(0);
- if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) ==
- (DemandedMask & ~RHSKnownZero))
- return I->getOperand(1);
-
- // If all of the demanded bits in the inputs are known zeros, return zero.
- if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
- return Constant::getNullValue(VTy);
-
- } else if (I->getOpcode() == Instruction::Or) {
- // We can simplify (X|Y) -> X or Y in the user's context if we know that
- // only bits from X or Y are demanded.
-
- // If either the LHS or the RHS are One, the result is One.
- ComputeMaskedBits(I->getOperand(1), DemandedMask,
- RHSKnownZero, RHSKnownOne, Depth+1);
- ComputeMaskedBits(I->getOperand(0), DemandedMask & ~RHSKnownOne,
- LHSKnownZero, LHSKnownOne, Depth+1);
-
- // If all of the demanded bits are known zero on one side, return the
- // other. These bits cannot contribute to the result of the 'or' in this
- // context.
- if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) ==
- (DemandedMask & ~LHSKnownOne))
- return I->getOperand(0);
- if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) ==
- (DemandedMask & ~RHSKnownOne))
- return I->getOperand(1);
-
- // If all of the potentially set bits on one side are known to be set on
- // the other side, just use the 'other' side.
- if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) ==
- (DemandedMask & (~RHSKnownZero)))
- return I->getOperand(0);
- if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) ==
- (DemandedMask & (~LHSKnownZero)))
- return I->getOperand(1);
- }
-
- // Compute the KnownZero/KnownOne bits to simplify things downstream.
- ComputeMaskedBits(I, DemandedMask, KnownZero, KnownOne, Depth);
- return 0;
- }
-
- // If this is the root being simplified, allow it to have multiple uses,
- // just set the DemandedMask to all bits so that we can try to simplify the
- // operands. This allows visitTruncInst (for example) to simplify the
- // operand of a trunc without duplicating all the logic below.
- if (Depth == 0 && !V->hasOneUse())
- DemandedMask = APInt::getAllOnesValue(BitWidth);
-
- switch (I->getOpcode()) {
- default:
- ComputeMaskedBits(I, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
- break;
- case Instruction::And:
- // If either the LHS or the RHS are Zero, the result is zero.
- if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
- RHSKnownZero, RHSKnownOne, Depth+1) ||
- SimplifyDemandedBits(I->getOperandUse(0), DemandedMask & ~RHSKnownZero,
- LHSKnownZero, LHSKnownOne, Depth+1))
- return I;
- assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
- assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
-
- // If all of the demanded bits are known 1 on one side, return the other.
- // These bits cannot contribute to the result of the 'and'.
- if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) ==
- (DemandedMask & ~LHSKnownZero))
- return I->getOperand(0);
- if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) ==
- (DemandedMask & ~RHSKnownZero))
- return I->getOperand(1);
-
- // If all of the demanded bits in the inputs are known zeros, return zero.
- if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
- return Constant::getNullValue(VTy);
-
- // If the RHS is a constant, see if we can simplify it.
- if (ShrinkDemandedConstant(I, 1, DemandedMask & ~LHSKnownZero))
- return I;
-
- // Output known-1 bits are only known if set in both the LHS & RHS.
- RHSKnownOne &= LHSKnownOne;
- // Output known-0 are known to be clear if zero in either the LHS | RHS.
- RHSKnownZero |= LHSKnownZero;
- break;
- case Instruction::Or:
- // If either the LHS or the RHS are One, the result is One.
- if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
- RHSKnownZero, RHSKnownOne, Depth+1) ||
- SimplifyDemandedBits(I->getOperandUse(0), DemandedMask & ~RHSKnownOne,
- LHSKnownZero, LHSKnownOne, Depth+1))
- return I;
- assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
- assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
-
- // If all of the demanded bits are known zero on one side, return the other.
- // These bits cannot contribute to the result of the 'or'.
- if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) ==
- (DemandedMask & ~LHSKnownOne))
- return I->getOperand(0);
- if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) ==
- (DemandedMask & ~RHSKnownOne))
- return I->getOperand(1);
-
- // If all of the potentially set bits on one side are known to be set on
- // the other side, just use the 'other' side.
- if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) ==
- (DemandedMask & (~RHSKnownZero)))
- return I->getOperand(0);
- if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) ==
- (DemandedMask & (~LHSKnownZero)))
- return I->getOperand(1);
-
- // If the RHS is a constant, see if we can simplify it.
- if (ShrinkDemandedConstant(I, 1, DemandedMask))
- return I;
-
- // Output known-0 bits are only known if clear in both the LHS & RHS.
- RHSKnownZero &= LHSKnownZero;
- // Output known-1 are known to be set if set in either the LHS | RHS.
- RHSKnownOne |= LHSKnownOne;
- break;
- case Instruction::Xor: {
- if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
- RHSKnownZero, RHSKnownOne, Depth+1) ||
- SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
- LHSKnownZero, LHSKnownOne, Depth+1))
- return I;
- assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
- assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
-
- // If all of the demanded bits are known zero on one side, return the other.
- // These bits cannot contribute to the result of the 'xor'.
- if ((DemandedMask & RHSKnownZero) == DemandedMask)
- return I->getOperand(0);
- if ((DemandedMask & LHSKnownZero) == DemandedMask)
- return I->getOperand(1);
-
- // Output known-0 bits are known if clear or set in both the LHS & RHS.
- APInt KnownZeroOut = (RHSKnownZero & LHSKnownZero) |
- (RHSKnownOne & LHSKnownOne);
- // Output known-1 are known to be set if set in only one of the LHS, RHS.
- APInt KnownOneOut = (RHSKnownZero & LHSKnownOne) |
- (RHSKnownOne & LHSKnownZero);
-
- // If all of the demanded bits are known to be zero on one side or the
- // other, turn this into an *inclusive* or.
- // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
- if ((DemandedMask & ~RHSKnownZero & ~LHSKnownZero) == 0) {
- Instruction *Or =
- BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1),
- I->getName());
- return InsertNewInstBefore(Or, *I);
- }
-
- // If all of the demanded bits on one side are known, and all of the set
- // bits on that side are also known to be set on the other side, turn this
- // into an AND, as we know the bits will be cleared.
- // e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
- if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask) {
- // all known
- if ((RHSKnownOne & LHSKnownOne) == RHSKnownOne) {
- Constant *AndC = Constant::getIntegerValue(VTy,
- ~RHSKnownOne & DemandedMask);
- Instruction *And =
- BinaryOperator::CreateAnd(I->getOperand(0), AndC, "tmp");
- return InsertNewInstBefore(And, *I);
- }
- }
-
- // If the RHS is a constant, see if we can simplify it.
- // FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
- if (ShrinkDemandedConstant(I, 1, DemandedMask))
- return I;
-
- // If our LHS is an 'and' and if it has one use, and if any of the bits we
- // are flipping are known to be set, then the xor is just resetting those
- // bits to zero. We can just knock out bits from the 'and' and the 'xor',
- // simplifying both of them.
- if (Instruction *LHSInst = dyn_cast<Instruction>(I->getOperand(0)))
- if (LHSInst->getOpcode() == Instruction::And && LHSInst->hasOneUse() &&
- isa<ConstantInt>(I->getOperand(1)) &&
- isa<ConstantInt>(LHSInst->getOperand(1)) &&
- (LHSKnownOne & RHSKnownOne & DemandedMask) != 0) {
- ConstantInt *AndRHS = cast<ConstantInt>(LHSInst->getOperand(1));
- ConstantInt *XorRHS = cast<ConstantInt>(I->getOperand(1));
- APInt NewMask = ~(LHSKnownOne & RHSKnownOne & DemandedMask);
-
- Constant *AndC =
- ConstantInt::get(I->getType(), NewMask & AndRHS->getValue());
- Instruction *NewAnd =
- BinaryOperator::CreateAnd(I->getOperand(0), AndC, "tmp");
- InsertNewInstBefore(NewAnd, *I);
-
- Constant *XorC =
- ConstantInt::get(I->getType(), NewMask & XorRHS->getValue());
- Instruction *NewXor =
- BinaryOperator::CreateXor(NewAnd, XorC, "tmp");
- return InsertNewInstBefore(NewXor, *I);
- }
-
-
- RHSKnownZero = KnownZeroOut;
- RHSKnownOne = KnownOneOut;
- break;
- }
- case Instruction::Select:
- if (SimplifyDemandedBits(I->getOperandUse(2), DemandedMask,
- RHSKnownZero, RHSKnownOne, Depth+1) ||
- SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
- LHSKnownZero, LHSKnownOne, Depth+1))
- return I;
- assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
- assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
-
- // If the operands are constants, see if we can simplify them.
- if (ShrinkDemandedConstant(I, 1, DemandedMask) ||
- ShrinkDemandedConstant(I, 2, DemandedMask))
- return I;
-
- // Only known if known in both the LHS and RHS.
- RHSKnownOne &= LHSKnownOne;
- RHSKnownZero &= LHSKnownZero;
- break;
- case Instruction::Trunc: {
- unsigned truncBf = I->getOperand(0)->getType()->getScalarSizeInBits();
- DemandedMask.zext(truncBf);
- RHSKnownZero.zext(truncBf);
- RHSKnownOne.zext(truncBf);
- if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
- RHSKnownZero, RHSKnownOne, Depth+1))
- return I;
- DemandedMask.trunc(BitWidth);
- RHSKnownZero.trunc(BitWidth);
- RHSKnownOne.trunc(BitWidth);
- assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
- break;
- }
- case Instruction::BitCast:
- if (!I->getOperand(0)->getType()->isIntOrIntVector())
- return false; // vector->int or fp->int?
-
- if (const VectorType *DstVTy = dyn_cast<VectorType>(I->getType())) {
- if (const VectorType *SrcVTy =
- dyn_cast<VectorType>(I->getOperand(0)->getType())) {
- if (DstVTy->getNumElements() != SrcVTy->getNumElements())
- // Don't touch a bitcast between vectors of different element counts.
- return false;
- } else
- // Don't touch a scalar-to-vector bitcast.
- return false;
- } else if (isa<VectorType>(I->getOperand(0)->getType()))
- // Don't touch a vector-to-scalar bitcast.
- return false;
-
- if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
- RHSKnownZero, RHSKnownOne, Depth+1))
- return I;
- assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
- break;
- case Instruction::ZExt: {
- // Compute the bits in the result that are not present in the input.
- unsigned SrcBitWidth =I->getOperand(0)->getType()->getScalarSizeInBits();
-
- DemandedMask.trunc(SrcBitWidth);
- RHSKnownZero.trunc(SrcBitWidth);
- RHSKnownOne.trunc(SrcBitWidth);
- if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
- RHSKnownZero, RHSKnownOne, Depth+1))
- return I;
- DemandedMask.zext(BitWidth);
- RHSKnownZero.zext(BitWidth);
- RHSKnownOne.zext(BitWidth);
- assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
- // The top bits are known to be zero.
- RHSKnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
- break;
- }
- case Instruction::SExt: {
- // Compute the bits in the result that are not present in the input.
- unsigned SrcBitWidth =I->getOperand(0)->getType()->getScalarSizeInBits();
-
- APInt InputDemandedBits = DemandedMask &
- APInt::getLowBitsSet(BitWidth, SrcBitWidth);
-
- APInt NewBits(APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth));
- // If any of the sign extended bits are demanded, we know that the sign
- // bit is demanded.
- if ((NewBits & DemandedMask) != 0)
- InputDemandedBits.set(SrcBitWidth-1);
-
- InputDemandedBits.trunc(SrcBitWidth);
- RHSKnownZero.trunc(SrcBitWidth);
- RHSKnownOne.trunc(SrcBitWidth);
- if (SimplifyDemandedBits(I->getOperandUse(0), InputDemandedBits,
- RHSKnownZero, RHSKnownOne, Depth+1))
- return I;
- InputDemandedBits.zext(BitWidth);
- RHSKnownZero.zext(BitWidth);
- RHSKnownOne.zext(BitWidth);
- assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
-
- // If the sign bit of the input is known set or clear, then we know the
- // top bits of the result.
-
- // If the input sign bit is known zero, or if the NewBits are not demanded
- // convert this into a zero extension.
- if (RHSKnownZero[SrcBitWidth-1] || (NewBits & ~DemandedMask) == NewBits) {
- // Convert to ZExt cast
- CastInst *NewCast = new ZExtInst(I->getOperand(0), VTy, I->getName());
- return InsertNewInstBefore(NewCast, *I);
- } else if (RHSKnownOne[SrcBitWidth-1]) { // Input sign bit known set
- RHSKnownOne |= NewBits;
- }
- break;
- }
- case Instruction::Add: {
- // Figure out what the input bits are. If the top bits of the and result
- // are not demanded, then the add doesn't demand them from its input
- // either.
- unsigned NLZ = DemandedMask.countLeadingZeros();
-
- // If there is a constant on the RHS, there are a variety of xformations
- // we can do.
- if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
- // If null, this should be simplified elsewhere. Some of the xforms here
- // won't work if the RHS is zero.
- if (RHS->isZero())
- break;
-
- // If the top bit of the output is demanded, demand everything from the
- // input. Otherwise, we demand all the input bits except NLZ top bits.
- APInt InDemandedBits(APInt::getLowBitsSet(BitWidth, BitWidth - NLZ));
-
- // Find information about known zero/one bits in the input.
- if (SimplifyDemandedBits(I->getOperandUse(0), InDemandedBits,
- LHSKnownZero, LHSKnownOne, Depth+1))
- return I;
-
- // If the RHS of the add has bits set that can't affect the input, reduce
- // the constant.
- if (ShrinkDemandedConstant(I, 1, InDemandedBits))
- return I;
-
- // Avoid excess work.
- if (LHSKnownZero == 0 && LHSKnownOne == 0)
- break;
-
- // Turn it into OR if input bits are zero.
- if ((LHSKnownZero & RHS->getValue()) == RHS->getValue()) {
- Instruction *Or =
- BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1),
- I->getName());
- return InsertNewInstBefore(Or, *I);
- }
-
- // We can say something about the output known-zero and known-one bits,
- // depending on potential carries from the input constant and the
- // unknowns. For example if the LHS is known to have at most the 0x0F0F0
- // bits set and the RHS constant is 0x01001, then we know we have a known
- // one mask of 0x00001 and a known zero mask of 0xE0F0E.
-
- // To compute this, we first compute the potential carry bits. These are
- // the bits which may be modified. I'm not aware of a better way to do
- // this scan.
- const APInt &RHSVal = RHS->getValue();
- APInt CarryBits((~LHSKnownZero + RHSVal) ^ (~LHSKnownZero ^ RHSVal));
-
- // Now that we know which bits have carries, compute the known-1/0 sets.
-
- // Bits are known one if they are known zero in one operand and one in the
- // other, and there is no input carry.
- RHSKnownOne = ((LHSKnownZero & RHSVal) |
- (LHSKnownOne & ~RHSVal)) & ~CarryBits;
-
- // Bits are known zero if they are known zero in both operands and there
- // is no input carry.
- RHSKnownZero = LHSKnownZero & ~RHSVal & ~CarryBits;
- } else {
- // If the high-bits of this ADD are not demanded, then it does not demand
- // the high bits of its LHS or RHS.
- if (DemandedMask[BitWidth-1] == 0) {
- // Right fill the mask of bits for this ADD to demand the most
- // significant bit and all those below it.
- APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
- if (SimplifyDemandedBits(I->getOperandUse(0), DemandedFromOps,
- LHSKnownZero, LHSKnownOne, Depth+1) ||
- SimplifyDemandedBits(I->getOperandUse(1), DemandedFromOps,
- LHSKnownZero, LHSKnownOne, Depth+1))
- return I;
- }
- }
- break;
- }
- case Instruction::Sub:
- // If the high-bits of this SUB are not demanded, then it does not demand
- // the high bits of its LHS or RHS.
- if (DemandedMask[BitWidth-1] == 0) {
- // Right fill the mask of bits for this SUB to demand the most
- // significant bit and all those below it.
- uint32_t NLZ = DemandedMask.countLeadingZeros();
- APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
- if (SimplifyDemandedBits(I->getOperandUse(0), DemandedFromOps,
- LHSKnownZero, LHSKnownOne, Depth+1) ||
- SimplifyDemandedBits(I->getOperandUse(1), DemandedFromOps,
- LHSKnownZero, LHSKnownOne, Depth+1))
- return I;
- }
- // Otherwise just hand the sub off to ComputeMaskedBits to fill in
- // the known zeros and ones.
- ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
- break;
- case Instruction::Shl:
- if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
- uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
- APInt DemandedMaskIn(DemandedMask.lshr(ShiftAmt));
- if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
- RHSKnownZero, RHSKnownOne, Depth+1))
- return I;
- assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
- RHSKnownZero <<= ShiftAmt;
- RHSKnownOne <<= ShiftAmt;
- // low bits known zero.
- if (ShiftAmt)
- RHSKnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt);
- }
- break;
- case Instruction::LShr:
- // For a logical shift right
- if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
- uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
-
- // Unsigned shift right.
- APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
- if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
- RHSKnownZero, RHSKnownOne, Depth+1))
- return I;
- assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
- RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
- RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
- if (ShiftAmt) {
- // Compute the new bits that are at the top now.
- APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
- RHSKnownZero |= HighBits; // high bits known zero.
- }
- }
- break;
- case Instruction::AShr:
- // If this is an arithmetic shift right and only the low-bit is set, we can
- // always convert this into a logical shr, even if the shift amount is
- // variable. The low bit of the shift cannot be an input sign bit unless
- // the shift amount is >= the size of the datatype, which is undefined.
- if (DemandedMask == 1) {
- // Perform the logical shift right.
- Instruction *NewVal = BinaryOperator::CreateLShr(
- I->getOperand(0), I->getOperand(1), I->getName());
- return InsertNewInstBefore(NewVal, *I);
- }
-
- // If the sign bit is the only bit demanded by this ashr, then there is no
- // need to do it, the shift doesn't change the high bit.
- if (DemandedMask.isSignBit())
- return I->getOperand(0);
-
- if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
- uint32_t ShiftAmt = SA->getLimitedValue(BitWidth);
-
- // Signed shift right.
- APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
- // If any of the "high bits" are demanded, we should set the sign bit as
- // demanded.
- if (DemandedMask.countLeadingZeros() <= ShiftAmt)
- DemandedMaskIn.set(BitWidth-1);
- if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
- RHSKnownZero, RHSKnownOne, Depth+1))
- return I;
- assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
- // Compute the new bits that are at the top now.
- APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
- RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
- RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
-
- // Handle the sign bits.
- APInt SignBit(APInt::getSignBit(BitWidth));
- // Adjust to where it is now in the mask.
- SignBit = APIntOps::lshr(SignBit, ShiftAmt);
-
- // If the input sign bit is known to be zero, or if none of the top bits
- // are demanded, turn this into an unsigned shift right.
- if (BitWidth <= ShiftAmt || RHSKnownZero[BitWidth-ShiftAmt-1] ||
- (HighBits & ~DemandedMask) == HighBits) {
- // Perform the logical shift right.
- Instruction *NewVal = BinaryOperator::CreateLShr(
- I->getOperand(0), SA, I->getName());
- return InsertNewInstBefore(NewVal, *I);
- } else if ((RHSKnownOne & SignBit) != 0) { // New bits are known one.
- RHSKnownOne |= HighBits;
- }
- }
- break;
- case Instruction::SRem:
- if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
- APInt RA = Rem->getValue().abs();
- if (RA.isPowerOf2()) {
- if (DemandedMask.ult(RA)) // srem won't affect demanded bits
- return I->getOperand(0);
-
- APInt LowBits = RA - 1;
- APInt Mask2 = LowBits | APInt::getSignBit(BitWidth);
- if (SimplifyDemandedBits(I->getOperandUse(0), Mask2,
- LHSKnownZero, LHSKnownOne, Depth+1))
- return I;
-
- if (LHSKnownZero[BitWidth-1] || ((LHSKnownZero & LowBits) == LowBits))
- LHSKnownZero |= ~LowBits;
-
- KnownZero |= LHSKnownZero & DemandedMask;
-
- assert(!(KnownZero & KnownOne) && "Bits known to be one AND zero?");
- }
- }
- break;
- case Instruction::URem: {
- APInt KnownZero2(BitWidth, 0), KnownOne2(BitWidth, 0);
- APInt AllOnes = APInt::getAllOnesValue(BitWidth);
- if (SimplifyDemandedBits(I->getOperandUse(0), AllOnes,
- KnownZero2, KnownOne2, Depth+1) ||
- SimplifyDemandedBits(I->getOperandUse(1), AllOnes,
- KnownZero2, KnownOne2, Depth+1))
- return I;
-
- unsigned Leaders = KnownZero2.countLeadingOnes();
- Leaders = std::max(Leaders,
- KnownZero2.countLeadingOnes());
- KnownZero = APInt::getHighBitsSet(BitWidth, Leaders) & DemandedMask;
- break;
- }
- case Instruction::Call:
- if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
- switch (II->getIntrinsicID()) {
- default: break;
- case Intrinsic::bswap: {
- // If the only bits demanded come from one byte of the bswap result,
- // just shift the input byte into position to eliminate the bswap.
- unsigned NLZ = DemandedMask.countLeadingZeros();
- unsigned NTZ = DemandedMask.countTrailingZeros();
-
- // Round NTZ down to the next byte. If we have 11 trailing zeros, then
- // we need all the bits down to bit 8. Likewise, round NLZ. If we
- // have 14 leading zeros, round to 8.
- NLZ &= ~7;
- NTZ &= ~7;
- // If we need exactly one byte, we can do this transformation.
- if (BitWidth-NLZ-NTZ == 8) {
- unsigned ResultBit = NTZ;
- unsigned InputBit = BitWidth-NTZ-8;
-
- // Replace this with either a left or right shift to get the byte into
- // the right place.
- Instruction *NewVal;
- if (InputBit > ResultBit)
- NewVal = BinaryOperator::CreateLShr(I->getOperand(1),
- ConstantInt::get(I->getType(), InputBit-ResultBit));
- else
- NewVal = BinaryOperator::CreateShl(I->getOperand(1),
- ConstantInt::get(I->getType(), ResultBit-InputBit));
- NewVal->takeName(I);
- return InsertNewInstBefore(NewVal, *I);
- }
-
- // TODO: Could compute known zero/one bits based on the input.
- break;
- }
- }
- }
- ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
- break;
- }
-
- // If the client is only demanding bits that we know, return the known
- // constant.
- if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask)
- return Constant::getIntegerValue(VTy, RHSKnownOne);
- return false;
-}
-
-
-/// SimplifyDemandedVectorElts - The specified value produces a vector with
-/// any number of elements. DemandedElts contains the set of elements that are
-/// actually used by the caller. This method analyzes which elements of the
-/// operand are undef and returns that information in UndefElts.
-///
-/// If the information about demanded elements can be used to simplify the
-/// operation, the operation is simplified, then the resultant value is
-/// returned. This returns null if no change was made.
-Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
- APInt& UndefElts,
- unsigned Depth) {
- unsigned VWidth = cast<VectorType>(V->getType())->getNumElements();
- APInt EltMask(APInt::getAllOnesValue(VWidth));
- assert((DemandedElts & ~EltMask) == 0 && "Invalid DemandedElts!");
-
- if (isa<UndefValue>(V)) {
- // If the entire vector is undefined, just return this info.
- UndefElts = EltMask;
- return 0;
- } else if (DemandedElts == 0) { // If nothing is demanded, provide undef.
- UndefElts = EltMask;
- return UndefValue::get(V->getType());
- }
-
- UndefElts = 0;
- if (ConstantVector *CP = dyn_cast<ConstantVector>(V)) {
- const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
- Constant *Undef = UndefValue::get(EltTy);
-
- std::vector<Constant*> Elts;
- for (unsigned i = 0; i != VWidth; ++i)
- if (!DemandedElts[i]) { // If not demanded, set to undef.
- Elts.push_back(Undef);
- UndefElts.set(i);
- } else if (isa<UndefValue>(CP->getOperand(i))) { // Already undef.
- Elts.push_back(Undef);
- UndefElts.set(i);
- } else { // Otherwise, defined.
- Elts.push_back(CP->getOperand(i));
- }
-
- // If we changed the constant, return it.
- Constant *NewCP = ConstantVector::get(Elts);
- return NewCP != CP ? NewCP : 0;
- } else if (isa<ConstantAggregateZero>(V)) {
- // Simplify the CAZ to a ConstantVector where the non-demanded elements are
- // set to undef.
-
- // Check if this is identity. If so, return 0 since we are not simplifying
- // anything.
- if (DemandedElts == ((1ULL << VWidth) -1))
- return 0;
-
- const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
- Constant *Zero = Constant::getNullValue(EltTy);
- Constant *Undef = UndefValue::get(EltTy);
- std::vector<Constant*> Elts;
- for (unsigned i = 0; i != VWidth; ++i) {
- Constant *Elt = DemandedElts[i] ? Zero : Undef;
- Elts.push_back(Elt);
- }
- UndefElts = DemandedElts ^ EltMask;
- return ConstantVector::get(Elts);
- }
-
- // Limit search depth.
- if (Depth == 10)
- return 0;
-
- // If multiple users are using the root value, procede with
- // simplification conservatively assuming that all elements
- // are needed.
- if (!V->hasOneUse()) {
- // Quit if we find multiple users of a non-root value though.
- // They'll be handled when it's their turn to be visited by
- // the main instcombine process.
- if (Depth != 0)
- // TODO: Just compute the UndefElts information recursively.
- return 0;
-
- // Conservatively assume that all elements are needed.
- DemandedElts = EltMask;
- }
-
- Instruction *I = dyn_cast<Instruction>(V);
- if (!I) return 0; // Only analyze instructions.
-
- bool MadeChange = false;
- APInt UndefElts2(VWidth, 0);
- Value *TmpV;
- switch (I->getOpcode()) {
- default: break;
-
- case Instruction::InsertElement: {
- // If this is a variable index, we don't know which element it overwrites.
- // demand exactly the same input as we produce.
- ConstantInt *Idx = dyn_cast<ConstantInt>(I->getOperand(2));
- if (Idx == 0) {
- // Note that we can't propagate undef elt info, because we don't know
- // which elt is getting updated.
- TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
- UndefElts2, Depth+1);
- if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
- break;
- }
-
- // If this is inserting an element that isn't demanded, remove this
- // insertelement.
- unsigned IdxNo = Idx->getZExtValue();
- if (IdxNo >= VWidth || !DemandedElts[IdxNo]) {
- Worklist.Add(I);
- return I->getOperand(0);
- }
-
- // Otherwise, the element inserted overwrites whatever was there, so the
- // input demanded set is simpler than the output set.
- APInt DemandedElts2 = DemandedElts;
- DemandedElts2.clear(IdxNo);
- TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts2,
- UndefElts, Depth+1);
- if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
-
- // The inserted element is defined.
- UndefElts.clear(IdxNo);
- break;
- }
- case Instruction::ShuffleVector: {
- ShuffleVectorInst *Shuffle = cast<ShuffleVectorInst>(I);
- uint64_t LHSVWidth =
- cast<VectorType>(Shuffle->getOperand(0)->getType())->getNumElements();
- APInt LeftDemanded(LHSVWidth, 0), RightDemanded(LHSVWidth, 0);
- for (unsigned i = 0; i < VWidth; i++) {
- if (DemandedElts[i]) {
- unsigned MaskVal = Shuffle->getMaskValue(i);
- if (MaskVal != -1u) {
- assert(MaskVal < LHSVWidth * 2 &&
- "shufflevector mask index out of range!");
- if (MaskVal < LHSVWidth)
- LeftDemanded.set(MaskVal);
- else
- RightDemanded.set(MaskVal - LHSVWidth);
- }
- }
- }
-
- APInt UndefElts4(LHSVWidth, 0);
- TmpV = SimplifyDemandedVectorElts(I->getOperand(0), LeftDemanded,
- UndefElts4, Depth+1);
- if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
-
- APInt UndefElts3(LHSVWidth, 0);
- TmpV = SimplifyDemandedVectorElts(I->getOperand(1), RightDemanded,
- UndefElts3, Depth+1);
- if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
-
- bool NewUndefElts = false;
- for (unsigned i = 0; i < VWidth; i++) {
- unsigned MaskVal = Shuffle->getMaskValue(i);
- if (MaskVal == -1u) {
- UndefElts.set(i);
- } else if (MaskVal < LHSVWidth) {
- if (UndefElts4[MaskVal]) {
- NewUndefElts = true;
- UndefElts.set(i);
- }
- } else {
- if (UndefElts3[MaskVal - LHSVWidth]) {
- NewUndefElts = true;
- UndefElts.set(i);
- }
- }
- }
-
- if (NewUndefElts) {
- // Add additional discovered undefs.
- std::vector<Constant*> Elts;
- for (unsigned i = 0; i < VWidth; ++i) {
- if (UndefElts[i])
- Elts.push_back(UndefValue::get(Type::getInt32Ty(*Context)));
- else
- Elts.push_back(ConstantInt::get(Type::getInt32Ty(*Context),
- Shuffle->getMaskValue(i)));
- }
- I->setOperand(2, ConstantVector::get(Elts));
- MadeChange = true;
- }
- break;
- }
- case Instruction::BitCast: {
- // Vector->vector casts only.
- const VectorType *VTy = dyn_cast<VectorType>(I->getOperand(0)->getType());
- if (!VTy) break;
- unsigned InVWidth = VTy->getNumElements();
- APInt InputDemandedElts(InVWidth, 0);
- unsigned Ratio;
-
- if (VWidth == InVWidth) {
- // If we are converting from <4 x i32> -> <4 x f32>, we demand the same
- // elements as are demanded of us.
- Ratio = 1;
- InputDemandedElts = DemandedElts;
- } else if (VWidth > InVWidth) {
- // Untested so far.
- break;
-
- // If there are more elements in the result than there are in the source,
- // then an input element is live if any of the corresponding output
- // elements are live.
- Ratio = VWidth/InVWidth;
- for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) {
- if (DemandedElts[OutIdx])
- InputDemandedElts.set(OutIdx/Ratio);
- }
- } else {
- // Untested so far.
- break;
-
- // If there are more elements in the source than there are in the result,
- // then an input element is live if the corresponding output element is
- // live.
- Ratio = InVWidth/VWidth;
- for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
- if (DemandedElts[InIdx/Ratio])
- InputDemandedElts.set(InIdx);
- }
-
- // div/rem demand all inputs, because they don't want divide by zero.
- TmpV = SimplifyDemandedVectorElts(I->getOperand(0), InputDemandedElts,
- UndefElts2, Depth+1);
- if (TmpV) {
- I->setOperand(0, TmpV);
- MadeChange = true;
- }
-
- UndefElts = UndefElts2;
- if (VWidth > InVWidth) {
- llvm_unreachable("Unimp");
- // If there are more elements in the result than there are in the source,
- // then an output element is undef if the corresponding input element is
- // undef.
- for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
- if (UndefElts2[OutIdx/Ratio])
- UndefElts.set(OutIdx);
- } else if (VWidth < InVWidth) {
- llvm_unreachable("Unimp");
- // If there are more elements in the source than there are in the result,
- // then a result element is undef if all of the corresponding input
- // elements are undef.
- UndefElts = ~0ULL >> (64-VWidth); // Start out all undef.
- for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
- if (!UndefElts2[InIdx]) // Not undef?
- UndefElts.clear(InIdx/Ratio); // Clear undef bit.
- }
- break;
- }
- case Instruction::And:
- case Instruction::Or:
- case Instruction::Xor:
- case Instruction::Add:
- case Instruction::Sub:
- case Instruction::Mul:
- // div/rem demand all inputs, because they don't want divide by zero.
- TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
- UndefElts, Depth+1);
- if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
- TmpV = SimplifyDemandedVectorElts(I->getOperand(1), DemandedElts,
- UndefElts2, Depth+1);
- if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
-
- // Output elements are undefined if both are undefined. Consider things
- // like undef&0. The result is known zero, not undef.
- UndefElts &= UndefElts2;
- break;
-
- case Instruction::Call: {
- IntrinsicInst *II = dyn_cast<IntrinsicInst>(I);
- if (!II) break;
- switch (II->getIntrinsicID()) {
- default: break;
-
- // Binary vector operations that work column-wise. A dest element is a
- // function of the corresponding input elements from the two inputs.
- case Intrinsic::x86_sse_sub_ss:
- case Intrinsic::x86_sse_mul_ss:
- case Intrinsic::x86_sse_min_ss:
- case Intrinsic::x86_sse_max_ss:
- case Intrinsic::x86_sse2_sub_sd:
- case Intrinsic::x86_sse2_mul_sd:
- case Intrinsic::x86_sse2_min_sd:
- case Intrinsic::x86_sse2_max_sd:
- TmpV = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
- UndefElts, Depth+1);
- if (TmpV) { II->setOperand(1, TmpV); MadeChange = true; }
- TmpV = SimplifyDemandedVectorElts(II->getOperand(2), DemandedElts,
- UndefElts2, Depth+1);
- if (TmpV) { II->setOperand(2, TmpV); MadeChange = true; }
-
- // If only the low elt is demanded and this is a scalarizable intrinsic,
- // scalarize it now.
- if (DemandedElts == 1) {
- switch (II->getIntrinsicID()) {
- default: break;
- case Intrinsic::x86_sse_sub_ss:
- case Intrinsic::x86_sse_mul_ss:
- case Intrinsic::x86_sse2_sub_sd:
- case Intrinsic::x86_sse2_mul_sd:
- // TODO: Lower MIN/MAX/ABS/etc
- Value *LHS = II->getOperand(1);
- Value *RHS = II->getOperand(2);
- // Extract the element as scalars.
- LHS = InsertNewInstBefore(ExtractElementInst::Create(LHS,
- ConstantInt::get(Type::getInt32Ty(*Context), 0U, false), "tmp"), *II);
- RHS = InsertNewInstBefore(ExtractElementInst::Create(RHS,
- ConstantInt::get(Type::getInt32Ty(*Context), 0U, false), "tmp"), *II);
-
- switch (II->getIntrinsicID()) {
- default: llvm_unreachable("Case stmts out of sync!");
- case Intrinsic::x86_sse_sub_ss:
- case Intrinsic::x86_sse2_sub_sd:
- TmpV = InsertNewInstBefore(BinaryOperator::CreateFSub(LHS, RHS,
- II->getName()), *II);
- break;
- case Intrinsic::x86_sse_mul_ss:
- case Intrinsic::x86_sse2_mul_sd:
- TmpV = InsertNewInstBefore(BinaryOperator::CreateFMul(LHS, RHS,
- II->getName()), *II);
- break;
- }
-
- Instruction *New =
- InsertElementInst::Create(
- UndefValue::get(II->getType()), TmpV,
- ConstantInt::get(Type::getInt32Ty(*Context), 0U, false), II->getName());
- InsertNewInstBefore(New, *II);
- return New;
- }
- }
-
- // Output elements are undefined if both are undefined. Consider things
- // like undef&0. The result is known zero, not undef.
- UndefElts &= UndefElts2;
- break;
- }
- break;
- }
- }
- return MadeChange ? I : 0;
-}
-
-
-/// AssociativeOpt - Perform an optimization on an associative operator. This
-/// function is designed to check a chain of associative operators for a
-/// potential to apply a certain optimization. Since the optimization may be
-/// applicable if the expression was reassociated, this checks the chain, then
-/// reassociates the expression as necessary to expose the optimization
-/// opportunity. This makes use of a special Functor, which must define
-/// 'shouldApply' and 'apply' methods.
-///
-template<typename Functor>
-static Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
- unsigned Opcode = Root.getOpcode();
- Value *LHS = Root.getOperand(0);
-
- // Quick check, see if the immediate LHS matches...
- if (F.shouldApply(LHS))
- return F.apply(Root);
-
- // Otherwise, if the LHS is not of the same opcode as the root, return.
- Instruction *LHSI = dyn_cast<Instruction>(LHS);
- while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
- // Should we apply this transform to the RHS?
- bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
-
- // If not to the RHS, check to see if we should apply to the LHS...
- if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
- cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
- ShouldApply = true;
- }
-
- // If the functor wants to apply the optimization to the RHS of LHSI,
- // reassociate the expression from ((? op A) op B) to (? op (A op B))
- if (ShouldApply) {
- // Now all of the instructions are in the current basic block, go ahead
- // and perform the reassociation.
- Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
-
- // First move the selected RHS to the LHS of the root...
- Root.setOperand(0, LHSI->getOperand(1));
-
- // Make what used to be the LHS of the root be the user of the root...
- Value *ExtraOperand = TmpLHSI->getOperand(1);
- if (&Root == TmpLHSI) {
- Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
- return 0;
- }
- Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
- TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
- BasicBlock::iterator ARI = &Root; ++ARI;
- TmpLHSI->moveBefore(ARI); // Move TmpLHSI to after Root
- ARI = Root;
-
- // Now propagate the ExtraOperand down the chain of instructions until we
- // get to LHSI.
- while (TmpLHSI != LHSI) {
- Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
- // Move the instruction to immediately before the chain we are
- // constructing to avoid breaking dominance properties.
- NextLHSI->moveBefore(ARI);
- ARI = NextLHSI;
-
- Value *NextOp = NextLHSI->getOperand(1);
- NextLHSI->setOperand(1, ExtraOperand);
- TmpLHSI = NextLHSI;
- ExtraOperand = NextOp;
- }
-
- // Now that the instructions are reassociated, have the functor perform
- // the transformation...
- return F.apply(Root);
- }
-
- LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
- }
- return 0;
-}
-
-namespace {
-
-// AddRHS - Implements: X + X --> X << 1
-struct AddRHS {
- Value *RHS;
- explicit AddRHS(Value *rhs) : RHS(rhs) {}
- bool shouldApply(Value *LHS) const { return LHS == RHS; }
- Instruction *apply(BinaryOperator &Add) const {
- return BinaryOperator::CreateShl(Add.getOperand(0),
- ConstantInt::get(Add.getType(), 1));
- }
-};
-
-// AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
-// iff C1&C2 == 0
-struct AddMaskingAnd {
- Constant *C2;
- explicit AddMaskingAnd(Constant *c) : C2(c) {}
- bool shouldApply(Value *LHS) const {
- ConstantInt *C1;
- return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
- ConstantExpr::getAnd(C1, C2)->isNullValue();
- }
- Instruction *apply(BinaryOperator &Add) const {
- return BinaryOperator::CreateOr(Add.getOperand(0), Add.getOperand(1));
- }
-};
-
-}
-
-static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
- InstCombiner *IC) {
- if (CastInst *CI = dyn_cast<CastInst>(&I))
- return IC->Builder->CreateCast(CI->getOpcode(), SO, I.getType());
-
- // Figure out if the constant is the left or the right argument.
- bool ConstIsRHS = isa<Constant>(I.getOperand(1));
- Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
-
- if (Constant *SOC = dyn_cast<Constant>(SO)) {
- if (ConstIsRHS)
- return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
- return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
- }
-
- Value *Op0 = SO, *Op1 = ConstOperand;
- if (!ConstIsRHS)
- std::swap(Op0, Op1);
-
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
- return IC->Builder->CreateBinOp(BO->getOpcode(), Op0, Op1,
- SO->getName()+".op");
- if (ICmpInst *CI = dyn_cast<ICmpInst>(&I))
- return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
- SO->getName()+".cmp");
- if (FCmpInst *CI = dyn_cast<FCmpInst>(&I))
- return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
- SO->getName()+".cmp");
- llvm_unreachable("Unknown binary instruction type!");
-}
-
-// FoldOpIntoSelect - Given an instruction with a select as one operand and a
-// constant as the other operand, try to fold the binary operator into the
-// select arguments. This also works for Cast instructions, which obviously do
-// not have a second operand.
-static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
- InstCombiner *IC) {
- // Don't modify shared select instructions
- if (!SI->hasOneUse()) return 0;
- Value *TV = SI->getOperand(1);
- Value *FV = SI->getOperand(2);
-
- if (isa<Constant>(TV) || isa<Constant>(FV)) {
- // Bool selects with constant operands can be folded to logical ops.
- if (SI->getType() == Type::getInt1Ty(*IC->getContext())) return 0;
-
- Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
- Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
-
- return SelectInst::Create(SI->getCondition(), SelectTrueVal,
- SelectFalseVal);
- }
- return 0;
-}
-
-
-/// FoldOpIntoPhi - Given a binary operator, cast instruction, or select which
-/// has a PHI node as operand #0, see if we can fold the instruction into the
-/// PHI (which is only possible if all operands to the PHI are constants).
-///
-/// If AllowAggressive is true, FoldOpIntoPhi will allow certain transforms
-/// that would normally be unprofitable because they strongly encourage jump
-/// threading.
-Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I,
- bool AllowAggressive) {
- AllowAggressive = false;
- PHINode *PN = cast<PHINode>(I.getOperand(0));
- unsigned NumPHIValues = PN->getNumIncomingValues();
- if (NumPHIValues == 0 ||
- // We normally only transform phis with a single use, unless we're trying
- // hard to make jump threading happen.
- (!PN->hasOneUse() && !AllowAggressive))
- return 0;
-
-
- // Check to see if all of the operands of the PHI are simple constants
- // (constantint/constantfp/undef). If there is one non-constant value,
- // remember the BB it is in. If there is more than one or if *it* is a PHI,
- // bail out. We don't do arbitrary constant expressions here because moving
- // their computation can be expensive without a cost model.
- BasicBlock *NonConstBB = 0;
- for (unsigned i = 0; i != NumPHIValues; ++i)
- if (!isa<Constant>(PN->getIncomingValue(i)) ||
- isa<ConstantExpr>(PN->getIncomingValue(i))) {
- if (NonConstBB) return 0; // More than one non-const value.
- if (isa<PHINode>(PN->getIncomingValue(i))) return 0; // Itself a phi.
- NonConstBB = PN->getIncomingBlock(i);
-
- // If the incoming non-constant value is in I's block, we have an infinite
- // loop.
- if (NonConstBB == I.getParent())
- return 0;
- }
-
- // If there is exactly one non-constant value, we can insert a copy of the
- // operation in that block. However, if this is a critical edge, we would be
- // inserting the computation one some other paths (e.g. inside a loop). Only
- // do this if the pred block is unconditionally branching into the phi block.
- if (NonConstBB != 0 && !AllowAggressive) {
- BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
- if (!BI || !BI->isUnconditional()) return 0;
- }
-
- // Okay, we can do the transformation: create the new PHI node.
- PHINode *NewPN = PHINode::Create(I.getType(), "");
- NewPN->reserveOperandSpace(PN->getNumOperands()/2);
- InsertNewInstBefore(NewPN, *PN);
- NewPN->takeName(PN);
-
- // Next, add all of the operands to the PHI.
- if (SelectInst *SI = dyn_cast<SelectInst>(&I)) {
- // We only currently try to fold the condition of a select when it is a phi,
- // not the true/false values.
- Value *TrueV = SI->getTrueValue();
- Value *FalseV = SI->getFalseValue();
- BasicBlock *PhiTransBB = PN->getParent();
- for (unsigned i = 0; i != NumPHIValues; ++i) {
- BasicBlock *ThisBB = PN->getIncomingBlock(i);
- Value *TrueVInPred = TrueV->DoPHITranslation(PhiTransBB, ThisBB);
- Value *FalseVInPred = FalseV->DoPHITranslation(PhiTransBB, ThisBB);
- Value *InV = 0;
- if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
- InV = InC->isNullValue() ? FalseVInPred : TrueVInPred;
- } else {
- assert(PN->getIncomingBlock(i) == NonConstBB);
- InV = SelectInst::Create(PN->getIncomingValue(i), TrueVInPred,
- FalseVInPred,
- "phitmp", NonConstBB->getTerminator());
- Worklist.Add(cast<Instruction>(InV));
- }
- NewPN->addIncoming(InV, ThisBB);
- }
- } else if (I.getNumOperands() == 2) {
- Constant *C = cast<Constant>(I.getOperand(1));
- for (unsigned i = 0; i != NumPHIValues; ++i) {
- Value *InV = 0;
- if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
- if (CmpInst *CI = dyn_cast<CmpInst>(&I))
- InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
- else
- InV = ConstantExpr::get(I.getOpcode(), InC, C);
- } else {
- assert(PN->getIncomingBlock(i) == NonConstBB);
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
- InV = BinaryOperator::Create(BO->getOpcode(),
- PN->getIncomingValue(i), C, "phitmp",
- NonConstBB->getTerminator());
- else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
- InV = CmpInst::Create(CI->getOpcode(),
- CI->getPredicate(),
- PN->getIncomingValue(i), C, "phitmp",
- NonConstBB->getTerminator());
- else
- llvm_unreachable("Unknown binop!");
-
- Worklist.Add(cast<Instruction>(InV));
- }
- NewPN->addIncoming(InV, PN->getIncomingBlock(i));
- }
- } else {
- CastInst *CI = cast<CastInst>(&I);
- const Type *RetTy = CI->getType();
- for (unsigned i = 0; i != NumPHIValues; ++i) {
- Value *InV;
- if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
- InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy);
- } else {
- assert(PN->getIncomingBlock(i) == NonConstBB);
- InV = CastInst::Create(CI->getOpcode(), PN->getIncomingValue(i),
- I.getType(), "phitmp",
- NonConstBB->getTerminator());
- Worklist.Add(cast<Instruction>(InV));
- }
- NewPN->addIncoming(InV, PN->getIncomingBlock(i));
- }
- }
- return ReplaceInstUsesWith(I, NewPN);
-}
-
-
-/// WillNotOverflowSignedAdd - Return true if we can prove that:
-/// (sext (add LHS, RHS)) === (add (sext LHS), (sext RHS))
-/// This basically requires proving that the add in the original type would not
-/// overflow to change the sign bit or have a carry out.
-bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) {
- // There are different heuristics we can use for this. Here are some simple
- // ones.
-
- // Add has the property that adding any two 2's complement numbers can only
- // have one carry bit which can change a sign. As such, if LHS and RHS each
- // have at least two sign bits, we know that the addition of the two values
- // will sign extend fine.
- if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1)
- return true;
-
-
- // If one of the operands only has one non-zero bit, and if the other operand
- // has a known-zero bit in a more significant place than it (not including the
- // sign bit) the ripple may go up to and fill the zero, but won't change the
- // sign. For example, (X & ~4) + 1.
-
- // TODO: Implement.
-
- return false;
-}
-
-
-Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
- bool Changed = SimplifyCommutative(I);
- Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
-
- if (Value *V = SimplifyAddInst(LHS, RHS, I.hasNoSignedWrap(),
- I.hasNoUnsignedWrap(), TD))
- return ReplaceInstUsesWith(I, V);
-
-
- if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
- if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
- // X + (signbit) --> X ^ signbit
- const APInt& Val = CI->getValue();
- uint32_t BitWidth = Val.getBitWidth();
- if (Val == APInt::getSignBit(BitWidth))
- return BinaryOperator::CreateXor(LHS, RHS);
-
- // See if SimplifyDemandedBits can simplify this. This handles stuff like
- // (X & 254)+1 -> (X&254)|1
- if (SimplifyDemandedInstructionBits(I))
- return &I;
-
- // zext(bool) + C -> bool ? C + 1 : C
- if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS))
- if (ZI->getSrcTy() == Type::getInt1Ty(*Context))
- return SelectInst::Create(ZI->getOperand(0), AddOne(CI), CI);
- }
-
- if (isa<PHINode>(LHS))
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
-
- ConstantInt *XorRHS = 0;
- Value *XorLHS = 0;
- if (isa<ConstantInt>(RHSC) &&
- match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
- uint32_t TySizeBits = I.getType()->getScalarSizeInBits();
- const APInt& RHSVal = cast<ConstantInt>(RHSC)->getValue();
-
- uint32_t Size = TySizeBits / 2;
- APInt C0080Val(APInt(TySizeBits, 1ULL).shl(Size - 1));
- APInt CFF80Val(-C0080Val);
- do {
- if (TySizeBits > Size) {
- // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
- // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
- if ((RHSVal == CFF80Val && XorRHS->getValue() == C0080Val) ||
- (RHSVal == C0080Val && XorRHS->getValue() == CFF80Val)) {
- // This is a sign extend if the top bits are known zero.
- if (!MaskedValueIsZero(XorLHS,
- APInt::getHighBitsSet(TySizeBits, TySizeBits - Size)))
- Size = 0; // Not a sign ext, but can't be any others either.
- break;
- }
- }
- Size >>= 1;
- C0080Val = APIntOps::lshr(C0080Val, Size);
- CFF80Val = APIntOps::ashr(CFF80Val, Size);
- } while (Size >= 1);
-
- // FIXME: This shouldn't be necessary. When the backends can handle types
- // with funny bit widths then this switch statement should be removed. It
- // is just here to get the size of the "middle" type back up to something
- // that the back ends can handle.
- const Type *MiddleType = 0;
- switch (Size) {
- default: break;
- case 32: MiddleType = Type::getInt32Ty(*Context); break;
- case 16: MiddleType = Type::getInt16Ty(*Context); break;
- case 8: MiddleType = Type::getInt8Ty(*Context); break;
- }
- if (MiddleType) {
- Value *NewTrunc = Builder->CreateTrunc(XorLHS, MiddleType, "sext");
- return new SExtInst(NewTrunc, I.getType(), I.getName());
- }
- }
- }
-
- if (I.getType() == Type::getInt1Ty(*Context))
- return BinaryOperator::CreateXor(LHS, RHS);
-
- // X + X --> X << 1
- if (I.getType()->isInteger()) {
- if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS)))
- return Result;
-
- if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
- if (RHSI->getOpcode() == Instruction::Sub)
- if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
- return ReplaceInstUsesWith(I, RHSI->getOperand(0));
- }
- if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
- if (LHSI->getOpcode() == Instruction::Sub)
- if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
- return ReplaceInstUsesWith(I, LHSI->getOperand(0));
- }
- }
-
- // -A + B --> B - A
- // -A + -B --> -(A + B)
- if (Value *LHSV = dyn_castNegVal(LHS)) {
- if (LHS->getType()->isIntOrIntVector()) {
- if (Value *RHSV = dyn_castNegVal(RHS)) {
- Value *NewAdd = Builder->CreateAdd(LHSV, RHSV, "sum");
- return BinaryOperator::CreateNeg(NewAdd);
- }
- }
-
- return BinaryOperator::CreateSub(RHS, LHSV);
- }
-
- // A + -B --> A - B
- if (!isa<Constant>(RHS))
- if (Value *V = dyn_castNegVal(RHS))
- return BinaryOperator::CreateSub(LHS, V);
-
-
- ConstantInt *C2;
- if (Value *X = dyn_castFoldableMul(LHS, C2)) {
- if (X == RHS) // X*C + X --> X * (C+1)
- return BinaryOperator::CreateMul(RHS, AddOne(C2));
-
- // X*C1 + X*C2 --> X * (C1+C2)
- ConstantInt *C1;
- if (X == dyn_castFoldableMul(RHS, C1))
- return BinaryOperator::CreateMul(X, ConstantExpr::getAdd(C1, C2));
- }
-
- // X + X*C --> X * (C+1)
- if (dyn_castFoldableMul(RHS, C2) == LHS)
- return BinaryOperator::CreateMul(LHS, AddOne(C2));
-
- // X + ~X --> -1 since ~X = -X-1
- if (dyn_castNotVal(LHS) == RHS ||
- dyn_castNotVal(RHS) == LHS)
- return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
-
-
- // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
- if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
- if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2)))
- return R;
-
- // A+B --> A|B iff A and B have no bits set in common.
- if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
- APInt Mask = APInt::getAllOnesValue(IT->getBitWidth());
- APInt LHSKnownOne(IT->getBitWidth(), 0);
- APInt LHSKnownZero(IT->getBitWidth(), 0);
- ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
- if (LHSKnownZero != 0) {
- APInt RHSKnownOne(IT->getBitWidth(), 0);
- APInt RHSKnownZero(IT->getBitWidth(), 0);
- ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
-
- // No bits in common -> bitwise or.
- if ((LHSKnownZero|RHSKnownZero).isAllOnesValue())
- return BinaryOperator::CreateOr(LHS, RHS);
- }
- }
-
- // W*X + Y*Z --> W * (X+Z) iff W == Y
- if (I.getType()->isIntOrIntVector()) {
- Value *W, *X, *Y, *Z;
- if (match(LHS, m_Mul(m_Value(W), m_Value(X))) &&
- match(RHS, m_Mul(m_Value(Y), m_Value(Z)))) {
- if (W != Y) {
- if (W == Z) {
- std::swap(Y, Z);
- } else if (Y == X) {
- std::swap(W, X);
- } else if (X == Z) {
- std::swap(Y, Z);
- std::swap(W, X);
- }
- }
-
- if (W == Y) {
- Value *NewAdd = Builder->CreateAdd(X, Z, LHS->getName());
- return BinaryOperator::CreateMul(W, NewAdd);
- }
- }
- }
-
- if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
- Value *X = 0;
- if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
- return BinaryOperator::CreateSub(SubOne(CRHS), X);
-
- // (X & FF00) + xx00 -> (X+xx00) & FF00
- if (LHS->hasOneUse() &&
- match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
- Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
- if (Anded == CRHS) {
- // See if all bits from the first bit set in the Add RHS up are included
- // in the mask. First, get the rightmost bit.
- const APInt& AddRHSV = CRHS->getValue();
-
- // Form a mask of all bits from the lowest bit added through the top.
- APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
-
- // See if the and mask includes all of these bits.
- APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
-
- if (AddRHSHighBits == AddRHSHighBitsAnd) {
- // Okay, the xform is safe. Insert the new add pronto.
- Value *NewAdd = Builder->CreateAdd(X, CRHS, LHS->getName());
- return BinaryOperator::CreateAnd(NewAdd, C2);
- }
- }
- }
-
- // Try to fold constant add into select arguments.
- if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
- if (Instruction *R = FoldOpIntoSelect(I, SI, this))
- return R;
- }
-
- // add (select X 0 (sub n A)) A --> select X A n
- {
- SelectInst *SI = dyn_cast<SelectInst>(LHS);
- Value *A = RHS;
- if (!SI) {
- SI = dyn_cast<SelectInst>(RHS);
- A = LHS;
- }
- if (SI && SI->hasOneUse()) {
- Value *TV = SI->getTrueValue();
- Value *FV = SI->getFalseValue();
- Value *N;
-
- // Can we fold the add into the argument of the select?
- // We check both true and false select arguments for a matching subtract.
- if (match(FV, m_Zero()) &&
- match(TV, m_Sub(m_Value(N), m_Specific(A))))
- // Fold the add into the true select value.
- return SelectInst::Create(SI->getCondition(), N, A);
- if (match(TV, m_Zero()) &&
- match(FV, m_Sub(m_Value(N), m_Specific(A))))
- // Fold the add into the false select value.
- return SelectInst::Create(SI->getCondition(), A, N);
- }
- }
-
- // Check for (add (sext x), y), see if we can merge this into an
- // integer add followed by a sext.
- if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) {
- // (add (sext x), cst) --> (sext (add x, cst'))
- if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
- Constant *CI =
- ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
- if (LHSConv->hasOneUse() &&
- ConstantExpr::getSExt(CI, I.getType()) == RHSC &&
- WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
- // Insert the new, smaller add.
- Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
- CI, "addconv");
- return new SExtInst(NewAdd, I.getType());
- }
- }
-
- // (add (sext x), (sext y)) --> (sext (add int x, y))
- if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) {
- // Only do this if x/y have the same type, if at last one of them has a
- // single use (so we don't increase the number of sexts), and if the
- // integer add will not overflow.
- if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
- (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
- WillNotOverflowSignedAdd(LHSConv->getOperand(0),
- RHSConv->getOperand(0))) {
- // Insert the new integer add.
- Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
- RHSConv->getOperand(0), "addconv");
- return new SExtInst(NewAdd, I.getType());
- }
- }
- }
-
- return Changed ? &I : 0;
-}
-
-Instruction *InstCombiner::visitFAdd(BinaryOperator &I) {
- bool Changed = SimplifyCommutative(I);
- Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
-
- if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
- // X + 0 --> X
- if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
- if (CFP->isExactlyValue(ConstantFP::getNegativeZero
- (I.getType())->getValueAPF()))
- return ReplaceInstUsesWith(I, LHS);
- }
-
- if (isa<PHINode>(LHS))
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
- }
-
- // -A + B --> B - A
- // -A + -B --> -(A + B)
- if (Value *LHSV = dyn_castFNegVal(LHS))
- return BinaryOperator::CreateFSub(RHS, LHSV);
-
- // A + -B --> A - B
- if (!isa<Constant>(RHS))
- if (Value *V = dyn_castFNegVal(RHS))
- return BinaryOperator::CreateFSub(LHS, V);
-
- // Check for X+0.0. Simplify it to X if we know X is not -0.0.
- if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS))
- if (CFP->getValueAPF().isPosZero() && CannotBeNegativeZero(LHS))
- return ReplaceInstUsesWith(I, LHS);
-
- // Check for (add double (sitofp x), y), see if we can merge this into an
- // integer add followed by a promotion.
- if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) {
- // (add double (sitofp x), fpcst) --> (sitofp (add int x, intcst))
- // ... if the constant fits in the integer value. This is useful for things
- // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer
- // requires a constant pool load, and generally allows the add to be better
- // instcombined.
- if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) {
- Constant *CI =
- ConstantExpr::getFPToSI(CFP, LHSConv->getOperand(0)->getType());
- if (LHSConv->hasOneUse() &&
- ConstantExpr::getSIToFP(CI, I.getType()) == CFP &&
- WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
- // Insert the new integer add.
- Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
- CI, "addconv");
- return new SIToFPInst(NewAdd, I.getType());
- }
- }
-
- // (add double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))
- if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) {
- // Only do this if x/y have the same type, if at last one of them has a
- // single use (so we don't increase the number of int->fp conversions),
- // and if the integer add will not overflow.
- if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
- (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
- WillNotOverflowSignedAdd(LHSConv->getOperand(0),
- RHSConv->getOperand(0))) {
- // Insert the new integer add.
- Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
- RHSConv->getOperand(0),"addconv");
- return new SIToFPInst(NewAdd, I.getType());
- }
- }
- }
-
- return Changed ? &I : 0;
-}
-
-
-/// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
-/// code necessary to compute the offset from the base pointer (without adding
-/// in the base pointer). Return the result as a signed integer of intptr size.
-static Value *EmitGEPOffset(User *GEP, InstCombiner &IC) {
- TargetData &TD = *IC.getTargetData();
- gep_type_iterator GTI = gep_type_begin(GEP);
- const Type *IntPtrTy = TD.getIntPtrType(GEP->getContext());
- Value *Result = Constant::getNullValue(IntPtrTy);
-
- // Build a mask for high order bits.
- unsigned IntPtrWidth = TD.getPointerSizeInBits();
- uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
-
- for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
- ++i, ++GTI) {
- Value *Op = *i;
- uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()) & PtrSizeMask;
- if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
- if (OpC->isZero()) continue;
-
- // Handle a struct index, which adds its field offset to the pointer.
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
- Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
-
- Result = IC.Builder->CreateAdd(Result,
- ConstantInt::get(IntPtrTy, Size),
- GEP->getName()+".offs");
- continue;
- }
-
- Constant *Scale = ConstantInt::get(IntPtrTy, Size);
- Constant *OC =
- ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
- Scale = ConstantExpr::getMul(OC, Scale);
- // Emit an add instruction.
- Result = IC.Builder->CreateAdd(Result, Scale, GEP->getName()+".offs");
- continue;
- }
- // Convert to correct type.
- if (Op->getType() != IntPtrTy)
- Op = IC.Builder->CreateIntCast(Op, IntPtrTy, true, Op->getName()+".c");
- if (Size != 1) {
- Constant *Scale = ConstantInt::get(IntPtrTy, Size);
- // We'll let instcombine(mul) convert this to a shl if possible.
- Op = IC.Builder->CreateMul(Op, Scale, GEP->getName()+".idx");
- }
-
- // Emit an add instruction.
- Result = IC.Builder->CreateAdd(Op, Result, GEP->getName()+".offs");
- }
- return Result;
-}
-
-
-/// EvaluateGEPOffsetExpression - Return a value that can be used to compare
-/// the *offset* implied by a GEP to zero. For example, if we have &A[i], we
-/// want to return 'i' for "icmp ne i, 0". Note that, in general, indices can
-/// be complex, and scales are involved. The above expression would also be
-/// legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32).
-/// This later form is less amenable to optimization though, and we are allowed
-/// to generate the first by knowing that pointer arithmetic doesn't overflow.
-///
-/// If we can't emit an optimized form for this expression, this returns null.
-///
-static Value *EvaluateGEPOffsetExpression(User *GEP, Instruction &I,
- InstCombiner &IC) {
- TargetData &TD = *IC.getTargetData();
- gep_type_iterator GTI = gep_type_begin(GEP);
-
- // Check to see if this gep only has a single variable index. If so, and if
- // any constant indices are a multiple of its scale, then we can compute this
- // in terms of the scale of the variable index. For example, if the GEP
- // implies an offset of "12 + i*4", then we can codegen this as "3 + i",
- // because the expression will cross zero at the same point.
- unsigned i, e = GEP->getNumOperands();
- int64_t Offset = 0;
- for (i = 1; i != e; ++i, ++GTI) {
- if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
- // Compute the aggregate offset of constant indices.
- if (CI->isZero()) continue;
-
- // Handle a struct index, which adds its field offset to the pointer.
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
- Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
- } else {
- uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
- Offset += Size*CI->getSExtValue();
- }
- } else {
- // Found our variable index.
- break;
- }
- }
-
- // If there are no variable indices, we must have a constant offset, just
- // evaluate it the general way.
- if (i == e) return 0;
-
- Value *VariableIdx = GEP->getOperand(i);
- // Determine the scale factor of the variable element. For example, this is
- // 4 if the variable index is into an array of i32.
- uint64_t VariableScale = TD.getTypeAllocSize(GTI.getIndexedType());
-
- // Verify that there are no other variable indices. If so, emit the hard way.
- for (++i, ++GTI; i != e; ++i, ++GTI) {
- ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
- if (!CI) return 0;
-
- // Compute the aggregate offset of constant indices.
- if (CI->isZero()) continue;
-
- // Handle a struct index, which adds its field offset to the pointer.
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
- Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
- } else {
- uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
- Offset += Size*CI->getSExtValue();
- }
- }
-
- // Okay, we know we have a single variable index, which must be a
- // pointer/array/vector index. If there is no offset, life is simple, return
- // the index.
- unsigned IntPtrWidth = TD.getPointerSizeInBits();
- if (Offset == 0) {
- // Cast to intptrty in case a truncation occurs. If an extension is needed,
- // we don't need to bother extending: the extension won't affect where the
- // computation crosses zero.
- if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth)
- VariableIdx = new TruncInst(VariableIdx,
- TD.getIntPtrType(VariableIdx->getContext()),
- VariableIdx->getName(), &I);
- return VariableIdx;
- }
-
- // Otherwise, there is an index. The computation we will do will be modulo
- // the pointer size, so get it.
- uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
-
- Offset &= PtrSizeMask;
- VariableScale &= PtrSizeMask;
-
- // To do this transformation, any constant index must be a multiple of the
- // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i",
- // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a
- // multiple of the variable scale.
- int64_t NewOffs = Offset / (int64_t)VariableScale;
- if (Offset != NewOffs*(int64_t)VariableScale)
- return 0;
-
- // Okay, we can do this evaluation. Start by converting the index to intptr.
- const Type *IntPtrTy = TD.getIntPtrType(VariableIdx->getContext());
- if (VariableIdx->getType() != IntPtrTy)
- VariableIdx = CastInst::CreateIntegerCast(VariableIdx, IntPtrTy,
- true /*SExt*/,
- VariableIdx->getName(), &I);
- Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
- return BinaryOperator::CreateAdd(VariableIdx, OffsetVal, "offset", &I);
-}
-
-
-/// Optimize pointer differences into the same array into a size. Consider:
-/// &A[10] - &A[0]: we should compile this to "10". LHS/RHS are the pointer
-/// operands to the ptrtoint instructions for the LHS/RHS of the subtract.
-///
-Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS,
- const Type *Ty) {
- assert(TD && "Must have target data info for this");
-
- // If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize
- // this.
- bool Swapped;
- GetElementPtrInst *GEP = 0;
- ConstantExpr *CstGEP = 0;
-
- // TODO: Could also optimize &A[i] - &A[j] -> "i-j", and "&A.foo[i] - &A.foo".
- // For now we require one side to be the base pointer "A" or a constant
- // expression derived from it.
- if (GetElementPtrInst *LHSGEP = dyn_cast<GetElementPtrInst>(LHS)) {
- // (gep X, ...) - X
- if (LHSGEP->getOperand(0) == RHS) {
- GEP = LHSGEP;
- Swapped = false;
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(RHS)) {
- // (gep X, ...) - (ce_gep X, ...)
- if (CE->getOpcode() == Instruction::GetElementPtr &&
- LHSGEP->getOperand(0) == CE->getOperand(0)) {
- CstGEP = CE;
- GEP = LHSGEP;
- Swapped = false;
- }
- }
- }
-
- if (GetElementPtrInst *RHSGEP = dyn_cast<GetElementPtrInst>(RHS)) {
- // X - (gep X, ...)
- if (RHSGEP->getOperand(0) == LHS) {
- GEP = RHSGEP;
- Swapped = true;
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(LHS)) {
- // (ce_gep X, ...) - (gep X, ...)
- if (CE->getOpcode() == Instruction::GetElementPtr &&
- RHSGEP->getOperand(0) == CE->getOperand(0)) {
- CstGEP = CE;
- GEP = RHSGEP;
- Swapped = true;
- }
- }
- }
-
- if (GEP == 0)
- return 0;
-
- // Emit the offset of the GEP and an intptr_t.
- Value *Result = EmitGEPOffset(GEP, *this);
-
- // If we had a constant expression GEP on the other side offsetting the
- // pointer, subtract it from the offset we have.
- if (CstGEP) {
- Value *CstOffset = EmitGEPOffset(CstGEP, *this);
- Result = Builder->CreateSub(Result, CstOffset);
- }
-
-
- // If we have p - gep(p, ...) then we have to negate the result.
- if (Swapped)
- Result = Builder->CreateNeg(Result, "diff.neg");
-
- return Builder->CreateIntCast(Result, Ty, true);
-}
-
-
-Instruction *InstCombiner::visitSub(BinaryOperator &I) {
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (Op0 == Op1) // sub X, X -> 0
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
-
- // If this is a 'B = x-(-A)', change to B = x+A. This preserves NSW/NUW.
- if (Value *V = dyn_castNegVal(Op1)) {
- BinaryOperator *Res = BinaryOperator::CreateAdd(Op0, V);
- Res->setHasNoSignedWrap(I.hasNoSignedWrap());
- Res->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
- return Res;
- }
-
- if (isa<UndefValue>(Op0))
- return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
- if (isa<UndefValue>(Op1))
- return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
- if (I.getType() == Type::getInt1Ty(*Context))
- return BinaryOperator::CreateXor(Op0, Op1);
-
- if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
- // Replace (-1 - A) with (~A).
- if (C->isAllOnesValue())
- return BinaryOperator::CreateNot(Op1);
-
- // C - ~X == X + (1+C)
- Value *X = 0;
- if (match(Op1, m_Not(m_Value(X))))
- return BinaryOperator::CreateAdd(X, AddOne(C));
-
- // -(X >>u 31) -> (X >>s 31)
- // -(X >>s 31) -> (X >>u 31)
- if (C->isZero()) {
- if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1)) {
- if (SI->getOpcode() == Instruction::LShr) {
- if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
- // Check to see if we are shifting out everything but the sign bit.
- if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
- SI->getType()->getPrimitiveSizeInBits()-1) {
- // Ok, the transformation is safe. Insert AShr.
- return BinaryOperator::Create(Instruction::AShr,
- SI->getOperand(0), CU, SI->getName());
- }
- }
- } else if (SI->getOpcode() == Instruction::AShr) {
- if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
- // Check to see if we are shifting out everything but the sign bit.
- if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
- SI->getType()->getPrimitiveSizeInBits()-1) {
- // Ok, the transformation is safe. Insert LShr.
- return BinaryOperator::CreateLShr(
- SI->getOperand(0), CU, SI->getName());
- }
- }
- }
- }
- }
-
- // Try to fold constant sub into select arguments.
- if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
- if (Instruction *R = FoldOpIntoSelect(I, SI, this))
- return R;
-
- // C - zext(bool) -> bool ? C - 1 : C
- if (ZExtInst *ZI = dyn_cast<ZExtInst>(Op1))
- if (ZI->getSrcTy() == Type::getInt1Ty(*Context))
- return SelectInst::Create(ZI->getOperand(0), SubOne(C), C);
- }
-
- if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
- if (Op1I->getOpcode() == Instruction::Add) {
- if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
- return BinaryOperator::CreateNeg(Op1I->getOperand(1),
- I.getName());
- else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
- return BinaryOperator::CreateNeg(Op1I->getOperand(0),
- I.getName());
- else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
- if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
- // C1-(X+C2) --> (C1-C2)-X
- return BinaryOperator::CreateSub(
- ConstantExpr::getSub(CI1, CI2), Op1I->getOperand(0));
- }
- }
-
- if (Op1I->hasOneUse()) {
- // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
- // is not used by anyone else...
- //
- if (Op1I->getOpcode() == Instruction::Sub) {
- // Swap the two operands of the subexpr...
- Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
- Op1I->setOperand(0, IIOp1);
- Op1I->setOperand(1, IIOp0);
-
- // Create the new top level add instruction...
- return BinaryOperator::CreateAdd(Op0, Op1);
- }
-
- // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
- //
- if (Op1I->getOpcode() == Instruction::And &&
- (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
- Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
-
- Value *NewNot = Builder->CreateNot(OtherOp, "B.not");
- return BinaryOperator::CreateAnd(Op0, NewNot);
- }
-
- // 0 - (X sdiv C) -> (X sdiv -C)
- if (Op1I->getOpcode() == Instruction::SDiv)
- if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
- if (CSI->isZero())
- if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
- return BinaryOperator::CreateSDiv(Op1I->getOperand(0),
- ConstantExpr::getNeg(DivRHS));
-
- // X - X*C --> X * (1-C)
- ConstantInt *C2 = 0;
- if (dyn_castFoldableMul(Op1I, C2) == Op0) {
- Constant *CP1 =
- ConstantExpr::getSub(ConstantInt::get(I.getType(), 1),
- C2);
- return BinaryOperator::CreateMul(Op0, CP1);
- }
- }
- }
-
- if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
- if (Op0I->getOpcode() == Instruction::Add) {
- if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
- return ReplaceInstUsesWith(I, Op0I->getOperand(1));
- else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
- return ReplaceInstUsesWith(I, Op0I->getOperand(0));
- } else if (Op0I->getOpcode() == Instruction::Sub) {
- if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
- return BinaryOperator::CreateNeg(Op0I->getOperand(1),
- I.getName());
- }
- }
-
- ConstantInt *C1;
- if (Value *X = dyn_castFoldableMul(Op0, C1)) {
- if (X == Op1) // X*C - X --> X * (C-1)
- return BinaryOperator::CreateMul(Op1, SubOne(C1));
-
- ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
- if (X == dyn_castFoldableMul(Op1, C2))
- return BinaryOperator::CreateMul(X, ConstantExpr::getSub(C1, C2));
- }
-
- // Optimize pointer differences into the same array into a size. Consider:
- // &A[10] - &A[0]: we should compile this to "10".
- if (TD) {
- Value *LHSOp, *RHSOp;
- if (match(Op0, m_PtrToInt(m_Value(LHSOp))) &&
- match(Op1, m_PtrToInt(m_Value(RHSOp))))
- if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
- return ReplaceInstUsesWith(I, Res);
-
- // trunc(p)-trunc(q) -> trunc(p-q)
- if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) &&
- match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp)))))
- if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
- return ReplaceInstUsesWith(I, Res);
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitFSub(BinaryOperator &I) {
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- // If this is a 'B = x-(-A)', change to B = x+A...
- if (Value *V = dyn_castFNegVal(Op1))
- return BinaryOperator::CreateFAdd(Op0, V);
-
- if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
- if (Op1I->getOpcode() == Instruction::FAdd) {
- if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
- return BinaryOperator::CreateFNeg(Op1I->getOperand(1),
- I.getName());
- else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
- return BinaryOperator::CreateFNeg(Op1I->getOperand(0),
- I.getName());
- }
- }
-
- return 0;
-}
-
-/// isSignBitCheck - Given an exploded icmp instruction, return true if the
-/// comparison only checks the sign bit. If it only checks the sign bit, set
-/// TrueIfSigned if the result of the comparison is true when the input value is
-/// signed.
-static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
- bool &TrueIfSigned) {
- switch (pred) {
- case ICmpInst::ICMP_SLT: // True if LHS s< 0
- TrueIfSigned = true;
- return RHS->isZero();
- case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
- TrueIfSigned = true;
- return RHS->isAllOnesValue();
- case ICmpInst::ICMP_SGT: // True if LHS s> -1
- TrueIfSigned = false;
- return RHS->isAllOnesValue();
- case ICmpInst::ICMP_UGT:
- // True if LHS u> RHS and RHS == high-bit-mask - 1
- TrueIfSigned = true;
- return RHS->getValue() ==
- APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
- case ICmpInst::ICMP_UGE:
- // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
- TrueIfSigned = true;
- return RHS->getValue().isSignBit();
- default:
- return false;
- }
-}
-
-Instruction *InstCombiner::visitMul(BinaryOperator &I) {
- bool Changed = SimplifyCommutative(I);
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (isa<UndefValue>(Op1)) // undef * X -> 0
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
-
- // Simplify mul instructions with a constant RHS.
- if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1C)) {
-
- // ((X << C1)*C2) == (X * (C2 << C1))
- if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
- if (SI->getOpcode() == Instruction::Shl)
- if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
- return BinaryOperator::CreateMul(SI->getOperand(0),
- ConstantExpr::getShl(CI, ShOp));
-
- if (CI->isZero())
- return ReplaceInstUsesWith(I, Op1C); // X * 0 == 0
- if (CI->equalsInt(1)) // X * 1 == X
- return ReplaceInstUsesWith(I, Op0);
- if (CI->isAllOnesValue()) // X * -1 == 0 - X
- return BinaryOperator::CreateNeg(Op0, I.getName());
-
- const APInt& Val = cast<ConstantInt>(CI)->getValue();
- if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
- return BinaryOperator::CreateShl(Op0,
- ConstantInt::get(Op0->getType(), Val.logBase2()));
- }
- } else if (isa<VectorType>(Op1C->getType())) {
- if (Op1C->isNullValue())
- return ReplaceInstUsesWith(I, Op1C);
-
- if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
- if (Op1V->isAllOnesValue()) // X * -1 == 0 - X
- return BinaryOperator::CreateNeg(Op0, I.getName());
-
- // As above, vector X*splat(1.0) -> X in all defined cases.
- if (Constant *Splat = Op1V->getSplatValue()) {
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Splat))
- if (CI->equalsInt(1))
- return ReplaceInstUsesWith(I, Op0);
- }
- }
- }
-
- if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
- if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() &&
- isa<ConstantInt>(Op0I->getOperand(1)) && isa<ConstantInt>(Op1C)) {
- // Canonicalize (X+C1)*C2 -> X*C2+C1*C2.
- Value *Add = Builder->CreateMul(Op0I->getOperand(0), Op1C, "tmp");
- Value *C1C2 = Builder->CreateMul(Op1C, Op0I->getOperand(1));
- return BinaryOperator::CreateAdd(Add, C1C2);
-
- }
-
- // Try to fold constant mul into select arguments.
- if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
- if (Instruction *R = FoldOpIntoSelect(I, SI, this))
- return R;
-
- if (isa<PHINode>(Op0))
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
- }
-
- if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
- if (Value *Op1v = dyn_castNegVal(Op1))
- return BinaryOperator::CreateMul(Op0v, Op1v);
-
- // (X / Y) * Y = X - (X % Y)
- // (X / Y) * -Y = (X % Y) - X
- {
- Value *Op1C = Op1;
- BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0);
- if (!BO ||
- (BO->getOpcode() != Instruction::UDiv &&
- BO->getOpcode() != Instruction::SDiv)) {
- Op1C = Op0;
- BO = dyn_cast<BinaryOperator>(Op1);
- }
- Value *Neg = dyn_castNegVal(Op1C);
- if (BO && BO->hasOneUse() &&
- (BO->getOperand(1) == Op1C || BO->getOperand(1) == Neg) &&
- (BO->getOpcode() == Instruction::UDiv ||
- BO->getOpcode() == Instruction::SDiv)) {
- Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1);
-
- // If the division is exact, X % Y is zero.
- if (SDivOperator *SDiv = dyn_cast<SDivOperator>(BO))
- if (SDiv->isExact()) {
- if (Op1BO == Op1C)
- return ReplaceInstUsesWith(I, Op0BO);
- return BinaryOperator::CreateNeg(Op0BO);
- }
-
- Value *Rem;
- if (BO->getOpcode() == Instruction::UDiv)
- Rem = Builder->CreateURem(Op0BO, Op1BO);
- else
- Rem = Builder->CreateSRem(Op0BO, Op1BO);
- Rem->takeName(BO);
-
- if (Op1BO == Op1C)
- return BinaryOperator::CreateSub(Op0BO, Rem);
- return BinaryOperator::CreateSub(Rem, Op0BO);
- }
- }
-
- /// i1 mul -> i1 and.
- if (I.getType() == Type::getInt1Ty(*Context))
- return BinaryOperator::CreateAnd(Op0, Op1);
-
- // X*(1 << Y) --> X << Y
- // (1 << Y)*X --> X << Y
- {
- Value *Y;
- if (match(Op0, m_Shl(m_One(), m_Value(Y))))
- return BinaryOperator::CreateShl(Op1, Y);
- if (match(Op1, m_Shl(m_One(), m_Value(Y))))
- return BinaryOperator::CreateShl(Op0, Y);
- }
-
- // If one of the operands of the multiply is a cast from a boolean value, then
- // we know the bool is either zero or one, so this is a 'masking' multiply.
- // X * Y (where Y is 0 or 1) -> X & (0-Y)
- if (!isa<VectorType>(I.getType())) {
- // -2 is "-1 << 1" so it is all bits set except the low one.
- APInt Negative2(I.getType()->getPrimitiveSizeInBits(), (uint64_t)-2, true);
-
- Value *BoolCast = 0, *OtherOp = 0;
- if (MaskedValueIsZero(Op0, Negative2))
- BoolCast = Op0, OtherOp = Op1;
- else if (MaskedValueIsZero(Op1, Negative2))
- BoolCast = Op1, OtherOp = Op0;
-
- if (BoolCast) {
- Value *V = Builder->CreateSub(Constant::getNullValue(I.getType()),
- BoolCast, "tmp");
- return BinaryOperator::CreateAnd(V, OtherOp);
- }
- }
-
- return Changed ? &I : 0;
-}
-
-Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
- bool Changed = SimplifyCommutative(I);
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- // Simplify mul instructions with a constant RHS...
- if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
- if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1C)) {
- // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
- // ANSI says we can drop signals, so we can do this anyway." (from GCC)
- if (Op1F->isExactlyValue(1.0))
- return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
- } else if (isa<VectorType>(Op1C->getType())) {
- if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
- // As above, vector X*splat(1.0) -> X in all defined cases.
- if (Constant *Splat = Op1V->getSplatValue()) {
- if (ConstantFP *F = dyn_cast<ConstantFP>(Splat))
- if (F->isExactlyValue(1.0))
- return ReplaceInstUsesWith(I, Op0);
- }
- }
- }
-
- // Try to fold constant mul into select arguments.
- if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
- if (Instruction *R = FoldOpIntoSelect(I, SI, this))
- return R;
-
- if (isa<PHINode>(Op0))
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
- }
-
- if (Value *Op0v = dyn_castFNegVal(Op0)) // -X * -Y = X*Y
- if (Value *Op1v = dyn_castFNegVal(Op1))
- return BinaryOperator::CreateFMul(Op0v, Op1v);
-
- return Changed ? &I : 0;
-}
-
-/// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select
-/// instruction.
-bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
- SelectInst *SI = cast<SelectInst>(I.getOperand(1));
-
- // div/rem X, (Cond ? 0 : Y) -> div/rem X, Y
- int NonNullOperand = -1;
- if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
- if (ST->isNullValue())
- NonNullOperand = 2;
- // div/rem X, (Cond ? Y : 0) -> div/rem X, Y
- if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
- if (ST->isNullValue())
- NonNullOperand = 1;
-
- if (NonNullOperand == -1)
- return false;
-
- Value *SelectCond = SI->getOperand(0);
-
- // Change the div/rem to use 'Y' instead of the select.
- I.setOperand(1, SI->getOperand(NonNullOperand));
-
- // Okay, we know we replace the operand of the div/rem with 'Y' with no
- // problem. However, the select, or the condition of the select may have
- // multiple uses. Based on our knowledge that the operand must be non-zero,
- // propagate the known value for the select into other uses of it, and
- // propagate a known value of the condition into its other users.
-
- // If the select and condition only have a single use, don't bother with this,
- // early exit.
- if (SI->use_empty() && SelectCond->hasOneUse())
- return true;
-
- // Scan the current block backward, looking for other uses of SI.
- BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin();
-
- while (BBI != BBFront) {
- --BBI;
- // If we found a call to a function, we can't assume it will return, so
- // information from below it cannot be propagated above it.
- if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
- break;
-
- // Replace uses of the select or its condition with the known values.
- for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end();
- I != E; ++I) {
- if (*I == SI) {
- *I = SI->getOperand(NonNullOperand);
- Worklist.Add(BBI);
- } else if (*I == SelectCond) {
- *I = NonNullOperand == 1 ? ConstantInt::getTrue(*Context) :
- ConstantInt::getFalse(*Context);
- Worklist.Add(BBI);
- }
- }
-
- // If we past the instruction, quit looking for it.
- if (&*BBI == SI)
- SI = 0;
- if (&*BBI == SelectCond)
- SelectCond = 0;
-
- // If we ran out of things to eliminate, break out of the loop.
- if (SelectCond == 0 && SI == 0)
- break;
-
- }
- return true;
-}
-
-
-/// This function implements the transforms on div instructions that work
-/// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is
-/// used by the visitors to those instructions.
-/// @brief Transforms common to all three div instructions
-Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- // undef / X -> 0 for integer.
- // undef / X -> undef for FP (the undef could be a snan).
- if (isa<UndefValue>(Op0)) {
- if (Op0->getType()->isFPOrFPVector())
- return ReplaceInstUsesWith(I, Op0);
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
- }
-
- // X / undef -> undef
- if (isa<UndefValue>(Op1))
- return ReplaceInstUsesWith(I, Op1);
-
- return 0;
-}
-
-/// This function implements the transforms common to both integer division
-/// instructions (udiv and sdiv). It is called by the visitors to those integer
-/// division instructions.
-/// @brief Common integer divide transforms
-Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- // (sdiv X, X) --> 1 (udiv X, X) --> 1
- if (Op0 == Op1) {
- if (const VectorType *Ty = dyn_cast<VectorType>(I.getType())) {
- Constant *CI = ConstantInt::get(Ty->getElementType(), 1);
- std::vector<Constant*> Elts(Ty->getNumElements(), CI);
- return ReplaceInstUsesWith(I, ConstantVector::get(Elts));
- }
-
- Constant *CI = ConstantInt::get(I.getType(), 1);
- return ReplaceInstUsesWith(I, CI);
- }
-
- if (Instruction *Common = commonDivTransforms(I))
- return Common;
-
- // Handle cases involving: [su]div X, (select Cond, Y, Z)
- // This does not apply for fdiv.
- if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
- return &I;
-
- if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
- // div X, 1 == X
- if (RHS->equalsInt(1))
- return ReplaceInstUsesWith(I, Op0);
-
- // (X / C1) / C2 -> X / (C1*C2)
- if (Instruction *LHS = dyn_cast<Instruction>(Op0))
- if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
- if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
- if (MultiplyOverflows(RHS, LHSRHS,
- I.getOpcode()==Instruction::SDiv))
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
- else
- return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
- ConstantExpr::getMul(RHS, LHSRHS));
- }
-
- if (!RHS->isZero()) { // avoid X udiv 0
- if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
- if (Instruction *R = FoldOpIntoSelect(I, SI, this))
- return R;
- if (isa<PHINode>(Op0))
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
- }
- }
-
- // 0 / X == 0, we don't need to preserve faults!
- if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
- if (LHS->equalsInt(0))
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
-
- // It can't be division by zero, hence it must be division by one.
- if (I.getType() == Type::getInt1Ty(*Context))
- return ReplaceInstUsesWith(I, Op0);
-
- if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) {
- if (ConstantInt *X = cast_or_null<ConstantInt>(Op1V->getSplatValue()))
- // div X, 1 == X
- if (X->isOne())
- return ReplaceInstUsesWith(I, Op0);
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- // Handle the integer div common cases
- if (Instruction *Common = commonIDivTransforms(I))
- return Common;
-
- if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
- // X udiv C^2 -> X >> C
- // Check to see if this is an unsigned division with an exact power of 2,
- // if so, convert to a right shift.
- if (C->getValue().isPowerOf2()) // 0 not included in isPowerOf2
- return BinaryOperator::CreateLShr(Op0,
- ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
-
- // X udiv C, where C >= signbit
- if (C->getValue().isNegative()) {
- Value *IC = Builder->CreateICmpULT( Op0, C);
- return SelectInst::Create(IC, Constant::getNullValue(I.getType()),
- ConstantInt::get(I.getType(), 1));
- }
- }
-
- // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
- if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) {
- if (RHSI->getOpcode() == Instruction::Shl &&
- isa<ConstantInt>(RHSI->getOperand(0))) {
- const APInt& C1 = cast<ConstantInt>(RHSI->getOperand(0))->getValue();
- if (C1.isPowerOf2()) {
- Value *N = RHSI->getOperand(1);
- const Type *NTy = N->getType();
- if (uint32_t C2 = C1.logBase2())
- N = Builder->CreateAdd(N, ConstantInt::get(NTy, C2), "tmp");
- return BinaryOperator::CreateLShr(Op0, N);
- }
- }
- }
-
- // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
- // where C1&C2 are powers of two.
- if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
- if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
- if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
- const APInt &TVA = STO->getValue(), &FVA = SFO->getValue();
- if (TVA.isPowerOf2() && FVA.isPowerOf2()) {
- // Compute the shift amounts
- uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2();
- // Construct the "on true" case of the select
- Constant *TC = ConstantInt::get(Op0->getType(), TSA);
- Value *TSI = Builder->CreateLShr(Op0, TC, SI->getName()+".t");
-
- // Construct the "on false" case of the select
- Constant *FC = ConstantInt::get(Op0->getType(), FSA);
- Value *FSI = Builder->CreateLShr(Op0, FC, SI->getName()+".f");
-
- // construct the select instruction and return it.
- return SelectInst::Create(SI->getOperand(0), TSI, FSI, SI->getName());
- }
- }
- return 0;
-}
-
-Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- // Handle the integer div common cases
- if (Instruction *Common = commonIDivTransforms(I))
- return Common;
-
- if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
- // sdiv X, -1 == -X
- if (RHS->isAllOnesValue())
- return BinaryOperator::CreateNeg(Op0);
-
- // sdiv X, C --> ashr X, log2(C)
- if (cast<SDivOperator>(&I)->isExact() &&
- RHS->getValue().isNonNegative() &&
- RHS->getValue().isPowerOf2()) {
- Value *ShAmt = llvm::ConstantInt::get(RHS->getType(),
- RHS->getValue().exactLogBase2());
- return BinaryOperator::CreateAShr(Op0, ShAmt, I.getName());
- }
-
- // -X/C --> X/-C provided the negation doesn't overflow.
- if (SubOperator *Sub = dyn_cast<SubOperator>(Op0))
- if (isa<Constant>(Sub->getOperand(0)) &&
- cast<Constant>(Sub->getOperand(0))->isNullValue() &&
- Sub->hasNoSignedWrap())
- return BinaryOperator::CreateSDiv(Sub->getOperand(1),
- ConstantExpr::getNeg(RHS));
- }
-
- // If the sign bits of both operands are zero (i.e. we can prove they are
- // unsigned inputs), turn this into a udiv.
- if (I.getType()->isInteger()) {
- APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
- if (MaskedValueIsZero(Op0, Mask)) {
- if (MaskedValueIsZero(Op1, Mask)) {
- // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
- return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
- }
- ConstantInt *ShiftedInt;
- if (match(Op1, m_Shl(m_ConstantInt(ShiftedInt), m_Value())) &&
- ShiftedInt->getValue().isPowerOf2()) {
- // X sdiv (1 << Y) -> X udiv (1 << Y) ( -> X u>> Y)
- // Safe because the only negative value (1 << Y) can take on is
- // INT_MIN, and X sdiv INT_MIN == X udiv INT_MIN == 0 if X doesn't have
- // the sign bit set.
- return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
- }
- }
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
- return commonDivTransforms(I);
-}
-
-/// This function implements the transforms on rem instructions that work
-/// regardless of the kind of rem instruction it is (urem, srem, or frem). It
-/// is used by the visitors to those instructions.
-/// @brief Transforms common to all three rem instructions
-Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (isa<UndefValue>(Op0)) { // undef % X -> 0
- if (I.getType()->isFPOrFPVector())
- return ReplaceInstUsesWith(I, Op0); // X % undef -> undef (could be SNaN)
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
- }
- if (isa<UndefValue>(Op1))
- return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
-
- // Handle cases involving: rem X, (select Cond, Y, Z)
- if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
- return &I;
-
- return 0;
-}
-
-/// This function implements the transforms common to both integer remainder
-/// instructions (urem and srem). It is called by the visitors to those integer
-/// remainder instructions.
-/// @brief Common integer remainder transforms
-Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (Instruction *common = commonRemTransforms(I))
- return common;
-
- // 0 % X == 0 for integer, we don't need to preserve faults!
- if (Constant *LHS = dyn_cast<Constant>(Op0))
- if (LHS->isNullValue())
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
-
- if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
- // X % 0 == undef, we don't need to preserve faults!
- if (RHS->equalsInt(0))
- return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
-
- if (RHS->equalsInt(1)) // X % 1 == 0
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
-
- if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
- if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
- if (Instruction *R = FoldOpIntoSelect(I, SI, this))
- return R;
- } else if (isa<PHINode>(Op0I)) {
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
- }
-
- // See if we can fold away this rem instruction.
- if (SimplifyDemandedInstructionBits(I))
- return &I;
- }
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitURem(BinaryOperator &I) {
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (Instruction *common = commonIRemTransforms(I))
- return common;
-
- if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
- // X urem C^2 -> X and C
- // Check to see if this is an unsigned remainder with an exact power of 2,
- // if so, convert to a bitwise and.
- if (ConstantInt *C = dyn_cast<ConstantInt>(RHS))
- if (C->getValue().isPowerOf2())
- return BinaryOperator::CreateAnd(Op0, SubOne(C));
- }
-
- if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
- // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
- if (RHSI->getOpcode() == Instruction::Shl &&
- isa<ConstantInt>(RHSI->getOperand(0))) {
- if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) {
- Constant *N1 = Constant::getAllOnesValue(I.getType());
- Value *Add = Builder->CreateAdd(RHSI, N1, "tmp");
- return BinaryOperator::CreateAnd(Op0, Add);
- }
- }
- }
-
- // urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2)
- // where C1&C2 are powers of two.
- if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
- if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
- if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
- // STO == 0 and SFO == 0 handled above.
- if ((STO->getValue().isPowerOf2()) &&
- (SFO->getValue().isPowerOf2())) {
- Value *TrueAnd = Builder->CreateAnd(Op0, SubOne(STO),
- SI->getName()+".t");
- Value *FalseAnd = Builder->CreateAnd(Op0, SubOne(SFO),
- SI->getName()+".f");
- return SelectInst::Create(SI->getOperand(0), TrueAnd, FalseAnd);
- }
- }
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- // Handle the integer rem common cases
- if (Instruction *Common = commonIRemTransforms(I))
- return Common;
-
- if (Value *RHSNeg = dyn_castNegVal(Op1))
- if (!isa<Constant>(RHSNeg) ||
- (isa<ConstantInt>(RHSNeg) &&
- cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive())) {
- // X % -Y -> X % Y
- Worklist.AddValue(I.getOperand(1));
- I.setOperand(1, RHSNeg);
- return &I;
- }
-
- // If the sign bits of both operands are zero (i.e. we can prove they are
- // unsigned inputs), turn this into a urem.
- if (I.getType()->isInteger()) {
- APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
- if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
- // X srem Y -> X urem Y, iff X and Y don't have sign bit set
- return BinaryOperator::CreateURem(Op0, Op1, I.getName());
- }
- }
-
- // If it's a constant vector, flip any negative values positive.
- if (ConstantVector *RHSV = dyn_cast<ConstantVector>(Op1)) {
- unsigned VWidth = RHSV->getNumOperands();
-
- bool hasNegative = false;
- for (unsigned i = 0; !hasNegative && i != VWidth; ++i)
- if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i)))
- if (RHS->getValue().isNegative())
- hasNegative = true;
-
- if (hasNegative) {
- std::vector<Constant *> Elts(VWidth);
- for (unsigned i = 0; i != VWidth; ++i) {
- if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i))) {
- if (RHS->getValue().isNegative())
- Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
- else
- Elts[i] = RHS;
- }
- }
-
- Constant *NewRHSV = ConstantVector::get(Elts);
- if (NewRHSV != RHSV) {
- Worklist.AddValue(I.getOperand(1));
- I.setOperand(1, NewRHSV);
- return &I;
- }
- }
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
- return commonRemTransforms(I);
-}
-
-// isOneBitSet - Return true if there is exactly one bit set in the specified
-// constant.
-static bool isOneBitSet(const ConstantInt *CI) {
- return CI->getValue().isPowerOf2();
-}
-
-// isHighOnes - Return true if the constant is of the form 1+0+.
-// This is the same as lowones(~X).
-static bool isHighOnes(const ConstantInt *CI) {
- return (~CI->getValue() + 1).isPowerOf2();
-}
-
-/// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
-/// are carefully arranged to allow folding of expressions such as:
-///
-/// (A < B) | (A > B) --> (A != B)
-///
-/// Note that this is only valid if the first and second predicates have the
-/// same sign. Is illegal to do: (A u< B) | (A s> B)
-///
-/// Three bits are used to represent the condition, as follows:
-/// 0 A > B
-/// 1 A == B
-/// 2 A < B
-///
-/// <=> Value Definition
-/// 000 0 Always false
-/// 001 1 A > B
-/// 010 2 A == B
-/// 011 3 A >= B
-/// 100 4 A < B
-/// 101 5 A != B
-/// 110 6 A <= B
-/// 111 7 Always true
-///
-static unsigned getICmpCode(const ICmpInst *ICI) {
- switch (ICI->getPredicate()) {
- // False -> 0
- case ICmpInst::ICMP_UGT: return 1; // 001
- case ICmpInst::ICMP_SGT: return 1; // 001
- case ICmpInst::ICMP_EQ: return 2; // 010
- case ICmpInst::ICMP_UGE: return 3; // 011
- case ICmpInst::ICMP_SGE: return 3; // 011
- case ICmpInst::ICMP_ULT: return 4; // 100
- case ICmpInst::ICMP_SLT: return 4; // 100
- case ICmpInst::ICMP_NE: return 5; // 101
- case ICmpInst::ICMP_ULE: return 6; // 110
- case ICmpInst::ICMP_SLE: return 6; // 110
- // True -> 7
- default:
- llvm_unreachable("Invalid ICmp predicate!");
- return 0;
- }
-}
-
-/// getFCmpCode - Similar to getICmpCode but for FCmpInst. This encodes a fcmp
-/// predicate into a three bit mask. It also returns whether it is an ordered
-/// predicate by reference.
-static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) {
- isOrdered = false;
- switch (CC) {
- case FCmpInst::FCMP_ORD: isOrdered = true; return 0; // 000
- case FCmpInst::FCMP_UNO: return 0; // 000
- case FCmpInst::FCMP_OGT: isOrdered = true; return 1; // 001
- case FCmpInst::FCMP_UGT: return 1; // 001
- case FCmpInst::FCMP_OEQ: isOrdered = true; return 2; // 010
- case FCmpInst::FCMP_UEQ: return 2; // 010
- case FCmpInst::FCMP_OGE: isOrdered = true; return 3; // 011
- case FCmpInst::FCMP_UGE: return 3; // 011
- case FCmpInst::FCMP_OLT: isOrdered = true; return 4; // 100
- case FCmpInst::FCMP_ULT: return 4; // 100
- case FCmpInst::FCMP_ONE: isOrdered = true; return 5; // 101
- case FCmpInst::FCMP_UNE: return 5; // 101
- case FCmpInst::FCMP_OLE: isOrdered = true; return 6; // 110
- case FCmpInst::FCMP_ULE: return 6; // 110
- // True -> 7
- default:
- // Not expecting FCMP_FALSE and FCMP_TRUE;
- llvm_unreachable("Unexpected FCmp predicate!");
- return 0;
- }
-}
-
-/// getICmpValue - This is the complement of getICmpCode, which turns an
-/// opcode and two operands into either a constant true or false, or a brand
-/// new ICmp instruction. The sign is passed in to determine which kind
-/// of predicate to use in the new icmp instruction.
-static Value *getICmpValue(bool sign, unsigned code, Value *LHS, Value *RHS,
- LLVMContext *Context) {
- switch (code) {
- default: llvm_unreachable("Illegal ICmp code!");
- case 0: return ConstantInt::getFalse(*Context);
- case 1:
- if (sign)
- return new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS);
- else
- return new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS);
- case 2: return new ICmpInst(ICmpInst::ICMP_EQ, LHS, RHS);
- case 3:
- if (sign)
- return new ICmpInst(ICmpInst::ICMP_SGE, LHS, RHS);
- else
- return new ICmpInst(ICmpInst::ICMP_UGE, LHS, RHS);
- case 4:
- if (sign)
- return new ICmpInst(ICmpInst::ICMP_SLT, LHS, RHS);
- else
- return new ICmpInst(ICmpInst::ICMP_ULT, LHS, RHS);
- case 5: return new ICmpInst(ICmpInst::ICMP_NE, LHS, RHS);
- case 6:
- if (sign)
- return new ICmpInst(ICmpInst::ICMP_SLE, LHS, RHS);
- else
- return new ICmpInst(ICmpInst::ICMP_ULE, LHS, RHS);
- case 7: return ConstantInt::getTrue(*Context);
- }
-}
-
-/// getFCmpValue - This is the complement of getFCmpCode, which turns an
-/// opcode and two operands into either a FCmp instruction. isordered is passed
-/// in to determine which kind of predicate to use in the new fcmp instruction.
-static Value *getFCmpValue(bool isordered, unsigned code,
- Value *LHS, Value *RHS, LLVMContext *Context) {
- switch (code) {
- default: llvm_unreachable("Illegal FCmp code!");
- case 0:
- if (isordered)
- return new FCmpInst(FCmpInst::FCMP_ORD, LHS, RHS);
- else
- return new FCmpInst(FCmpInst::FCMP_UNO, LHS, RHS);
- case 1:
- if (isordered)
- return new FCmpInst(FCmpInst::FCMP_OGT, LHS, RHS);
- else
- return new FCmpInst(FCmpInst::FCMP_UGT, LHS, RHS);
- case 2:
- if (isordered)
- return new FCmpInst(FCmpInst::FCMP_OEQ, LHS, RHS);
- else
- return new FCmpInst(FCmpInst::FCMP_UEQ, LHS, RHS);
- case 3:
- if (isordered)
- return new FCmpInst(FCmpInst::FCMP_OGE, LHS, RHS);
- else
- return new FCmpInst(FCmpInst::FCMP_UGE, LHS, RHS);
- case 4:
- if (isordered)
- return new FCmpInst(FCmpInst::FCMP_OLT, LHS, RHS);
- else
- return new FCmpInst(FCmpInst::FCMP_ULT, LHS, RHS);
- case 5:
- if (isordered)
- return new FCmpInst(FCmpInst::FCMP_ONE, LHS, RHS);
- else
- return new FCmpInst(FCmpInst::FCMP_UNE, LHS, RHS);
- case 6:
- if (isordered)
- return new FCmpInst(FCmpInst::FCMP_OLE, LHS, RHS);
- else
- return new FCmpInst(FCmpInst::FCMP_ULE, LHS, RHS);
- case 7: return ConstantInt::getTrue(*Context);
- }
-}
-
-/// PredicatesFoldable - Return true if both predicates match sign or if at
-/// least one of them is an equality comparison (which is signless).
-static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
- return (CmpInst::isSigned(p1) == CmpInst::isSigned(p2)) ||
- (CmpInst::isSigned(p1) && ICmpInst::isEquality(p2)) ||
- (CmpInst::isSigned(p2) && ICmpInst::isEquality(p1));
-}
-
-namespace {
-// FoldICmpLogical - Implements (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
-struct FoldICmpLogical {
- InstCombiner &IC;
- Value *LHS, *RHS;
- ICmpInst::Predicate pred;
- FoldICmpLogical(InstCombiner &ic, ICmpInst *ICI)
- : IC(ic), LHS(ICI->getOperand(0)), RHS(ICI->getOperand(1)),
- pred(ICI->getPredicate()) {}
- bool shouldApply(Value *V) const {
- if (ICmpInst *ICI = dyn_cast<ICmpInst>(V))
- if (PredicatesFoldable(pred, ICI->getPredicate()))
- return ((ICI->getOperand(0) == LHS && ICI->getOperand(1) == RHS) ||
- (ICI->getOperand(0) == RHS && ICI->getOperand(1) == LHS));
- return false;
- }
- Instruction *apply(Instruction &Log) const {
- ICmpInst *ICI = cast<ICmpInst>(Log.getOperand(0));
- if (ICI->getOperand(0) != LHS) {
- assert(ICI->getOperand(1) == LHS);
- ICI->swapOperands(); // Swap the LHS and RHS of the ICmp
- }
-
- ICmpInst *RHSICI = cast<ICmpInst>(Log.getOperand(1));
- unsigned LHSCode = getICmpCode(ICI);
- unsigned RHSCode = getICmpCode(RHSICI);
- unsigned Code;
- switch (Log.getOpcode()) {
- case Instruction::And: Code = LHSCode & RHSCode; break;
- case Instruction::Or: Code = LHSCode | RHSCode; break;
- case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
- default: llvm_unreachable("Illegal logical opcode!"); return 0;
- }
-
- bool isSigned = RHSICI->isSigned() || ICI->isSigned();
- Value *RV = getICmpValue(isSigned, Code, LHS, RHS, IC.getContext());
- if (Instruction *I = dyn_cast<Instruction>(RV))
- return I;
- // Otherwise, it's a constant boolean value...
- return IC.ReplaceInstUsesWith(Log, RV);
- }
-};
-} // end anonymous namespace
-
-// OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
-// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
-// guaranteed to be a binary operator.
-Instruction *InstCombiner::OptAndOp(Instruction *Op,
- ConstantInt *OpRHS,
- ConstantInt *AndRHS,
- BinaryOperator &TheAnd) {
- Value *X = Op->getOperand(0);
- Constant *Together = 0;
- if (!Op->isShift())
- Together = ConstantExpr::getAnd(AndRHS, OpRHS);
-
- switch (Op->getOpcode()) {
- case Instruction::Xor:
- if (Op->hasOneUse()) {
- // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
- Value *And = Builder->CreateAnd(X, AndRHS);
- And->takeName(Op);
- return BinaryOperator::CreateXor(And, Together);
- }
- break;
- case Instruction::Or:
- if (Together == AndRHS) // (X | C) & C --> C
- return ReplaceInstUsesWith(TheAnd, AndRHS);
-
- if (Op->hasOneUse() && Together != OpRHS) {
- // (X | C1) & C2 --> (X | (C1&C2)) & C2
- Value *Or = Builder->CreateOr(X, Together);
- Or->takeName(Op);
- return BinaryOperator::CreateAnd(Or, AndRHS);
- }
- break;
- case Instruction::Add:
- if (Op->hasOneUse()) {
- // Adding a one to a single bit bit-field should be turned into an XOR
- // of the bit. First thing to check is to see if this AND is with a
- // single bit constant.
- const APInt& AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
-
- // If there is only one bit set...
- if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
- // Ok, at this point, we know that we are masking the result of the
- // ADD down to exactly one bit. If the constant we are adding has
- // no bits set below this bit, then we can eliminate the ADD.
- const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue();
-
- // Check to see if any bits below the one bit set in AndRHSV are set.
- if ((AddRHS & (AndRHSV-1)) == 0) {
- // If not, the only thing that can effect the output of the AND is
- // the bit specified by AndRHSV. If that bit is set, the effect of
- // the XOR is to toggle the bit. If it is clear, then the ADD has
- // no effect.
- if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
- TheAnd.setOperand(0, X);
- return &TheAnd;
- } else {
- // Pull the XOR out of the AND.
- Value *NewAnd = Builder->CreateAnd(X, AndRHS);
- NewAnd->takeName(Op);
- return BinaryOperator::CreateXor(NewAnd, AndRHS);
- }
- }
- }
- }
- break;
-
- case Instruction::Shl: {
- // We know that the AND will not produce any of the bits shifted in, so if
- // the anded constant includes them, clear them now!
- //
- uint32_t BitWidth = AndRHS->getType()->getBitWidth();
- uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
- APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
- ConstantInt *CI = ConstantInt::get(*Context, AndRHS->getValue() & ShlMask);
-
- if (CI->getValue() == ShlMask) {
- // Masking out bits that the shift already masks
- return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
- } else if (CI != AndRHS) { // Reducing bits set in and.
- TheAnd.setOperand(1, CI);
- return &TheAnd;
- }
- break;
- }
- case Instruction::LShr:
- {
- // We know that the AND will not produce any of the bits shifted in, so if
- // the anded constant includes them, clear them now! This only applies to
- // unsigned shifts, because a signed shr may bring in set bits!
- //
- uint32_t BitWidth = AndRHS->getType()->getBitWidth();
- uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
- APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
- ConstantInt *CI = ConstantInt::get(*Context, AndRHS->getValue() & ShrMask);
-
- if (CI->getValue() == ShrMask) {
- // Masking out bits that the shift already masks.
- return ReplaceInstUsesWith(TheAnd, Op);
- } else if (CI != AndRHS) {
- TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
- return &TheAnd;
- }
- break;
- }
- case Instruction::AShr:
- // Signed shr.
- // See if this is shifting in some sign extension, then masking it out
- // with an and.
- if (Op->hasOneUse()) {
- uint32_t BitWidth = AndRHS->getType()->getBitWidth();
- uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
- APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
- Constant *C = ConstantInt::get(*Context, AndRHS->getValue() & ShrMask);
- if (C == AndRHS) { // Masking out bits shifted in.
- // (Val ashr C1) & C2 -> (Val lshr C1) & C2
- // Make the argument unsigned.
- Value *ShVal = Op->getOperand(0);
- ShVal = Builder->CreateLShr(ShVal, OpRHS, Op->getName());
- return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName());
- }
- }
- break;
- }
- return 0;
-}
-
-
-/// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
-/// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
-/// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates
-/// whether to treat the V, Lo and HI as signed or not. IB is the location to
-/// insert new instructions.
-Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
- bool isSigned, bool Inside,
- Instruction &IB) {
- assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ?
- ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
- "Lo is not <= Hi in range emission code!");
-
- if (Inside) {
- if (Lo == Hi) // Trivially false.
- return new ICmpInst(ICmpInst::ICMP_NE, V, V);
-
- // V >= Min && V < Hi --> V < Hi
- if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
- ICmpInst::Predicate pred = (isSigned ?
- ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
- return new ICmpInst(pred, V, Hi);
- }
-
- // Emit V-Lo <u Hi-Lo
- Constant *NegLo = ConstantExpr::getNeg(Lo);
- Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
- Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
- return new ICmpInst(ICmpInst::ICMP_ULT, Add, UpperBound);
- }
-
- if (Lo == Hi) // Trivially true.
- return new ICmpInst(ICmpInst::ICMP_EQ, V, V);
-
- // V < Min || V >= Hi -> V > Hi-1
- Hi = SubOne(cast<ConstantInt>(Hi));
- if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
- ICmpInst::Predicate pred = (isSigned ?
- ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
- return new ICmpInst(pred, V, Hi);
- }
-
- // Emit V-Lo >u Hi-1-Lo
- // Note that Hi has already had one subtracted from it, above.
- ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo));
- Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
- Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
- return new ICmpInst(ICmpInst::ICMP_UGT, Add, LowerBound);
-}
-
-// isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
-// any number of 0s on either side. The 1s are allowed to wrap from LSB to
-// MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
-// not, since all 1s are not contiguous.
-static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
- const APInt& V = Val->getValue();
- uint32_t BitWidth = Val->getType()->getBitWidth();
- if (!APIntOps::isShiftedMask(BitWidth, V)) return false;
-
- // look for the first zero bit after the run of ones
- MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
- // look for the first non-zero bit
- ME = V.getActiveBits();
- return true;
-}
-
-/// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
-/// where isSub determines whether the operator is a sub. If we can fold one of
-/// the following xforms:
-///
-/// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
-/// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
-/// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
-///
-/// return (A +/- B).
-///
-Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
- ConstantInt *Mask, bool isSub,
- Instruction &I) {
- Instruction *LHSI = dyn_cast<Instruction>(LHS);
- if (!LHSI || LHSI->getNumOperands() != 2 ||
- !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
-
- ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
-
- switch (LHSI->getOpcode()) {
- default: return 0;
- case Instruction::And:
- if (ConstantExpr::getAnd(N, Mask) == Mask) {
- // If the AndRHS is a power of two minus one (0+1+), this is simple.
- if ((Mask->getValue().countLeadingZeros() +
- Mask->getValue().countPopulation()) ==
- Mask->getValue().getBitWidth())
- break;
-
- // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
- // part, we don't need any explicit masks to take them out of A. If that
- // is all N is, ignore it.
- uint32_t MB = 0, ME = 0;
- if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
- uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
- APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
- if (MaskedValueIsZero(RHS, Mask))
- break;
- }
- }
- return 0;
- case Instruction::Or:
- case Instruction::Xor:
- // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
- if ((Mask->getValue().countLeadingZeros() +
- Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
- && ConstantExpr::getAnd(N, Mask)->isNullValue())
- break;
- return 0;
- }
-
- if (isSub)
- return Builder->CreateSub(LHSI->getOperand(0), RHS, "fold");
- return Builder->CreateAdd(LHSI->getOperand(0), RHS, "fold");
-}
-
-/// FoldAndOfICmps - Fold (icmp)&(icmp) if possible.
-Instruction *InstCombiner::FoldAndOfICmps(Instruction &I,
- ICmpInst *LHS, ICmpInst *RHS) {
- Value *Val, *Val2;
- ConstantInt *LHSCst, *RHSCst;
- ICmpInst::Predicate LHSCC, RHSCC;
-
- // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
- if (!match(LHS, m_ICmp(LHSCC, m_Value(Val),
- m_ConstantInt(LHSCst))) ||
- !match(RHS, m_ICmp(RHSCC, m_Value(Val2),
- m_ConstantInt(RHSCst))))
- return 0;
-
- if (LHSCst == RHSCst && LHSCC == RHSCC) {
- // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C)
- // where C is a power of 2
- if (LHSCC == ICmpInst::ICMP_ULT &&
- LHSCst->getValue().isPowerOf2()) {
- Value *NewOr = Builder->CreateOr(Val, Val2);
- return new ICmpInst(LHSCC, NewOr, LHSCst);
- }
-
- // (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0)
- if (LHSCC == ICmpInst::ICMP_EQ && LHSCst->isZero()) {
- Value *NewOr = Builder->CreateOr(Val, Val2);
- return new ICmpInst(LHSCC, NewOr, LHSCst);
- }
- }
-
- // From here on, we only handle:
- // (icmp1 A, C1) & (icmp2 A, C2) --> something simpler.
- if (Val != Val2) return 0;
-
- // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
- if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
- RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
- LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
- RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
- return 0;
-
- // We can't fold (ugt x, C) & (sgt x, C2).
- if (!PredicatesFoldable(LHSCC, RHSCC))
- return 0;
-
- // Ensure that the larger constant is on the RHS.
- bool ShouldSwap;
- if (CmpInst::isSigned(LHSCC) ||
- (ICmpInst::isEquality(LHSCC) &&
- CmpInst::isSigned(RHSCC)))
- ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
- else
- ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
-
- if (ShouldSwap) {
- std::swap(LHS, RHS);
- std::swap(LHSCst, RHSCst);
- std::swap(LHSCC, RHSCC);
- }
-
- // At this point, we know we have have two icmp instructions
- // comparing a value against two constants and and'ing the result
- // together. Because of the above check, we know that we only have
- // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
- // (from the FoldICmpLogical check above), that the two constants
- // are not equal and that the larger constant is on the RHS
- assert(LHSCst != RHSCst && "Compares not folded above?");
-
- switch (LHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ:
- switch (RHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ: // (X == 13 & X == 15) -> false
- case ICmpInst::ICMP_UGT: // (X == 13 & X > 15) -> false
- case ICmpInst::ICMP_SGT: // (X == 13 & X > 15) -> false
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13
- case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13
- case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13
- return ReplaceInstUsesWith(I, LHS);
- }
- case ICmpInst::ICMP_NE:
- switch (RHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_ULT:
- if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
- return new ICmpInst(ICmpInst::ICMP_ULT, Val, LHSCst);
- break; // (X != 13 & X u< 15) -> no change
- case ICmpInst::ICMP_SLT:
- if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
- return new ICmpInst(ICmpInst::ICMP_SLT, Val, LHSCst);
- break; // (X != 13 & X s< 15) -> no change
- case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15
- case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15
- case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
- return ReplaceInstUsesWith(I, RHS);
- case ICmpInst::ICMP_NE:
- if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
- Constant *AddCST = ConstantExpr::getNeg(LHSCst);
- Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
- return new ICmpInst(ICmpInst::ICMP_UGT, Add,
- ConstantInt::get(Add->getType(), 1));
- }
- break; // (X != 13 & X != 15) -> no change
- }
- break;
- case ICmpInst::ICMP_ULT:
- switch (RHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false
- case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change
- break;
- case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13
- case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13
- return ReplaceInstUsesWith(I, LHS);
- case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change
- break;
- }
- break;
- case ICmpInst::ICMP_SLT:
- switch (RHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ: // (X s< 13 & X == 15) -> false
- case ICmpInst::ICMP_SGT: // (X s< 13 & X s> 15) -> false
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change
- break;
- case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13
- case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13
- return ReplaceInstUsesWith(I, LHS);
- case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change
- break;
- }
- break;
- case ICmpInst::ICMP_UGT:
- switch (RHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X == 15
- case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15
- return ReplaceInstUsesWith(I, RHS);
- case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change
- break;
- case ICmpInst::ICMP_NE:
- if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
- return new ICmpInst(LHSCC, Val, RHSCst);
- break; // (X u> 13 & X != 15) -> no change
- case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) <u 1
- return InsertRangeTest(Val, AddOne(LHSCst),
- RHSCst, false, true, I);
- case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change
- break;
- }
- break;
- case ICmpInst::ICMP_SGT:
- switch (RHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X == 15
- case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15
- return ReplaceInstUsesWith(I, RHS);
- case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change
- break;
- case ICmpInst::ICMP_NE:
- if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
- return new ICmpInst(LHSCC, Val, RHSCst);
- break; // (X s> 13 & X != 15) -> no change
- case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1
- return InsertRangeTest(Val, AddOne(LHSCst),
- RHSCst, true, true, I);
- case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change
- break;
- }
- break;
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::FoldAndOfFCmps(Instruction &I, FCmpInst *LHS,
- FCmpInst *RHS) {
-
- if (LHS->getPredicate() == FCmpInst::FCMP_ORD &&
- RHS->getPredicate() == FCmpInst::FCMP_ORD) {
- // (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y)
- if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
- if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
- // If either of the constants are nans, then the whole thing returns
- // false.
- if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- return new FCmpInst(FCmpInst::FCMP_ORD,
- LHS->getOperand(0), RHS->getOperand(0));
- }
-
- // Handle vector zeros. This occurs because the canonical form of
- // "fcmp ord x,x" is "fcmp ord x, 0".
- if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
- isa<ConstantAggregateZero>(RHS->getOperand(1)))
- return new FCmpInst(FCmpInst::FCMP_ORD,
- LHS->getOperand(0), RHS->getOperand(0));
- return 0;
- }
-
- Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
- Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
- FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
-
-
- if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
- // Swap RHS operands to match LHS.
- Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
- std::swap(Op1LHS, Op1RHS);
- }
-
- if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
- // Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y).
- if (Op0CC == Op1CC)
- return new FCmpInst((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
-
- if (Op0CC == FCmpInst::FCMP_FALSE || Op1CC == FCmpInst::FCMP_FALSE)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- if (Op0CC == FCmpInst::FCMP_TRUE)
- return ReplaceInstUsesWith(I, RHS);
- if (Op1CC == FCmpInst::FCMP_TRUE)
- return ReplaceInstUsesWith(I, LHS);
-
- bool Op0Ordered;
- bool Op1Ordered;
- unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
- unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
- if (Op1Pred == 0) {
- std::swap(LHS, RHS);
- std::swap(Op0Pred, Op1Pred);
- std::swap(Op0Ordered, Op1Ordered);
- }
- if (Op0Pred == 0) {
- // uno && ueq -> uno && (uno || eq) -> ueq
- // ord && olt -> ord && (ord && lt) -> olt
- if (Op0Ordered == Op1Ordered)
- return ReplaceInstUsesWith(I, RHS);
-
- // uno && oeq -> uno && (ord && eq) -> false
- // uno && ord -> false
- if (!Op0Ordered)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- // ord && ueq -> ord && (uno || eq) -> oeq
- return cast<Instruction>(getFCmpValue(true, Op1Pred,
- Op0LHS, Op0RHS, Context));
- }
- }
-
- return 0;
-}
-
-
-Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
- bool Changed = SimplifyCommutative(I);
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (Value *V = SimplifyAndInst(Op0, Op1, TD))
- return ReplaceInstUsesWith(I, V);
-
- // See if we can simplify any instructions used by the instruction whose sole
- // purpose is to compute bits we don't care about.
- if (SimplifyDemandedInstructionBits(I))
- return &I;
-
- if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
- const APInt &AndRHSMask = AndRHS->getValue();
- APInt NotAndRHS(~AndRHSMask);
-
- // Optimize a variety of ((val OP C1) & C2) combinations...
- if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
- Value *Op0LHS = Op0I->getOperand(0);
- Value *Op0RHS = Op0I->getOperand(1);
- switch (Op0I->getOpcode()) {
- default: break;
- case Instruction::Xor:
- case Instruction::Or:
- // If the mask is only needed on one incoming arm, push it up.
- if (!Op0I->hasOneUse()) break;
-
- if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
- // Not masking anything out for the LHS, move to RHS.
- Value *NewRHS = Builder->CreateAnd(Op0RHS, AndRHS,
- Op0RHS->getName()+".masked");
- return BinaryOperator::Create(Op0I->getOpcode(), Op0LHS, NewRHS);
- }
- if (!isa<Constant>(Op0RHS) &&
- MaskedValueIsZero(Op0RHS, NotAndRHS)) {
- // Not masking anything out for the RHS, move to LHS.
- Value *NewLHS = Builder->CreateAnd(Op0LHS, AndRHS,
- Op0LHS->getName()+".masked");
- return BinaryOperator::Create(Op0I->getOpcode(), NewLHS, Op0RHS);
- }
-
- break;
- case Instruction::Add:
- // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
- // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
- // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
- if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
- return BinaryOperator::CreateAnd(V, AndRHS);
- if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
- return BinaryOperator::CreateAnd(V, AndRHS); // Add commutes
- break;
-
- case Instruction::Sub:
- // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
- // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
- // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
- if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
- return BinaryOperator::CreateAnd(V, AndRHS);
-
- // (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS
- // has 1's for all bits that the subtraction with A might affect.
- if (Op0I->hasOneUse()) {
- uint32_t BitWidth = AndRHSMask.getBitWidth();
- uint32_t Zeros = AndRHSMask.countLeadingZeros();
- APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros);
-
- ConstantInt *A = dyn_cast<ConstantInt>(Op0LHS);
- if (!(A && A->isZero()) && // avoid infinite recursion.
- MaskedValueIsZero(Op0LHS, Mask)) {
- Value *NewNeg = Builder->CreateNeg(Op0RHS);
- return BinaryOperator::CreateAnd(NewNeg, AndRHS);
- }
- }
- break;
-
- case Instruction::Shl:
- case Instruction::LShr:
- // (1 << x) & 1 --> zext(x == 0)
- // (1 >> x) & 1 --> zext(x == 0)
- if (AndRHSMask == 1 && Op0LHS == AndRHS) {
- Value *NewICmp =
- Builder->CreateICmpEQ(Op0RHS, Constant::getNullValue(I.getType()));
- return new ZExtInst(NewICmp, I.getType());
- }
- break;
- }
-
- if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
- if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
- return Res;
- } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
- // If this is an integer truncation or change from signed-to-unsigned, and
- // if the source is an and/or with immediate, transform it. This
- // frequently occurs for bitfield accesses.
- if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
- if ((isa<TruncInst>(CI) || isa<BitCastInst>(CI)) &&
- CastOp->getNumOperands() == 2)
- if (ConstantInt *AndCI =dyn_cast<ConstantInt>(CastOp->getOperand(1))){
- if (CastOp->getOpcode() == Instruction::And) {
- // Change: and (cast (and X, C1) to T), C2
- // into : and (cast X to T), trunc_or_bitcast(C1)&C2
- // This will fold the two constants together, which may allow
- // other simplifications.
- Value *NewCast = Builder->CreateTruncOrBitCast(
- CastOp->getOperand(0), I.getType(),
- CastOp->getName()+".shrunk");
- // trunc_or_bitcast(C1)&C2
- Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
- C3 = ConstantExpr::getAnd(C3, AndRHS);
- return BinaryOperator::CreateAnd(NewCast, C3);
- } else if (CastOp->getOpcode() == Instruction::Or) {
- // Change: and (cast (or X, C1) to T), C2
- // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
- Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
- if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS)
- // trunc(C1)&C2
- return ReplaceInstUsesWith(I, AndRHS);
- }
- }
- }
- }
-
- // Try to fold constant and into select arguments.
- if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
- if (Instruction *R = FoldOpIntoSelect(I, SI, this))
- return R;
- if (isa<PHINode>(Op0))
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
- }
-
-
- // (~A & ~B) == (~(A | B)) - De Morgan's Law
- if (Value *Op0NotVal = dyn_castNotVal(Op0))
- if (Value *Op1NotVal = dyn_castNotVal(Op1))
- if (Op0->hasOneUse() && Op1->hasOneUse()) {
- Value *Or = Builder->CreateOr(Op0NotVal, Op1NotVal,
- I.getName()+".demorgan");
- return BinaryOperator::CreateNot(Or);
- }
-
- {
- Value *A = 0, *B = 0, *C = 0, *D = 0;
- // (A|B) & ~(A&B) -> A^B
- if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
- match(Op1, m_Not(m_And(m_Value(C), m_Value(D)))) &&
- ((A == C && B == D) || (A == D && B == C)))
- return BinaryOperator::CreateXor(A, B);
-
- // ~(A&B) & (A|B) -> A^B
- if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
- match(Op0, m_Not(m_And(m_Value(C), m_Value(D)))) &&
- ((A == C && B == D) || (A == D && B == C)))
- return BinaryOperator::CreateXor(A, B);
-
- if (Op0->hasOneUse() &&
- match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
- if (A == Op1) { // (A^B)&A -> A&(A^B)
- I.swapOperands(); // Simplify below
- std::swap(Op0, Op1);
- } else if (B == Op1) { // (A^B)&B -> B&(B^A)
- cast<BinaryOperator>(Op0)->swapOperands();
- I.swapOperands(); // Simplify below
- std::swap(Op0, Op1);
- }
- }
-
- if (Op1->hasOneUse() &&
- match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
- if (B == Op0) { // B&(A^B) -> B&(B^A)
- cast<BinaryOperator>(Op1)->swapOperands();
- std::swap(A, B);
- }
- if (A == Op0) // A&(A^B) -> A & ~B
- return BinaryOperator::CreateAnd(A, Builder->CreateNot(B, "tmp"));
- }
-
- // (A&((~A)|B)) -> A&B
- if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) ||
- match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1)))))
- return BinaryOperator::CreateAnd(A, Op1);
- if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) ||
- match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0)))))
- return BinaryOperator::CreateAnd(A, Op0);
- }
-
- if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {
- // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
- if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
- return R;
-
- if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0))
- if (Instruction *Res = FoldAndOfICmps(I, LHS, RHS))
- return Res;
- }
-
- // fold (and (cast A), (cast B)) -> (cast (and A, B))
- if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
- if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
- if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind ?
- const Type *SrcTy = Op0C->getOperand(0)->getType();
- if (SrcTy == Op1C->getOperand(0)->getType() &&
- SrcTy->isIntOrIntVector() &&
- // Only do this if the casts both really cause code to be generated.
- ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
- I.getType(), TD) &&
- ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
- I.getType(), TD)) {
- Value *NewOp = Builder->CreateAnd(Op0C->getOperand(0),
- Op1C->getOperand(0), I.getName());
- return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
- }
- }
-
- // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
- if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
- if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
- if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
- SI0->getOperand(1) == SI1->getOperand(1) &&
- (SI0->hasOneUse() || SI1->hasOneUse())) {
- Value *NewOp =
- Builder->CreateAnd(SI0->getOperand(0), SI1->getOperand(0),
- SI0->getName());
- return BinaryOperator::Create(SI1->getOpcode(), NewOp,
- SI1->getOperand(1));
- }
- }
-
- // If and'ing two fcmp, try combine them into one.
- if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
- if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
- if (Instruction *Res = FoldAndOfFCmps(I, LHS, RHS))
- return Res;
- }
-
- return Changed ? &I : 0;
-}
-
-/// CollectBSwapParts - Analyze the specified subexpression and see if it is
-/// capable of providing pieces of a bswap. The subexpression provides pieces
-/// of a bswap if it is proven that each of the non-zero bytes in the output of
-/// the expression came from the corresponding "byte swapped" byte in some other
-/// value. For example, if the current subexpression is "(shl i32 %X, 24)" then
-/// we know that the expression deposits the low byte of %X into the high byte
-/// of the bswap result and that all other bytes are zero. This expression is
-/// accepted, the high byte of ByteValues is set to X to indicate a correct
-/// match.
-///
-/// This function returns true if the match was unsuccessful and false if so.
-/// On entry to the function the "OverallLeftShift" is a signed integer value
-/// indicating the number of bytes that the subexpression is later shifted. For
-/// example, if the expression is later right shifted by 16 bits, the
-/// OverallLeftShift value would be -2 on entry. This is used to specify which
-/// byte of ByteValues is actually being set.
-///
-/// Similarly, ByteMask is a bitmask where a bit is clear if its corresponding
-/// byte is masked to zero by a user. For example, in (X & 255), X will be
-/// processed with a bytemask of 1. Because bytemask is 32-bits, this limits
-/// this function to working on up to 32-byte (256 bit) values. ByteMask is
-/// always in the local (OverallLeftShift) coordinate space.
-///
-static bool CollectBSwapParts(Value *V, int OverallLeftShift, uint32_t ByteMask,
- SmallVector<Value*, 8> &ByteValues) {
- if (Instruction *I = dyn_cast<Instruction>(V)) {
- // If this is an or instruction, it may be an inner node of the bswap.
- if (I->getOpcode() == Instruction::Or) {
- return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
- ByteValues) ||
- CollectBSwapParts(I->getOperand(1), OverallLeftShift, ByteMask,
- ByteValues);
- }
-
- // If this is a logical shift by a constant multiple of 8, recurse with
- // OverallLeftShift and ByteMask adjusted.
- if (I->isLogicalShift() && isa<ConstantInt>(I->getOperand(1))) {
- unsigned ShAmt =
- cast<ConstantInt>(I->getOperand(1))->getLimitedValue(~0U);
- // Ensure the shift amount is defined and of a byte value.
- if ((ShAmt & 7) || (ShAmt > 8*ByteValues.size()))
- return true;
-
- unsigned ByteShift = ShAmt >> 3;
- if (I->getOpcode() == Instruction::Shl) {
- // X << 2 -> collect(X, +2)
- OverallLeftShift += ByteShift;
- ByteMask >>= ByteShift;
- } else {
- // X >>u 2 -> collect(X, -2)
- OverallLeftShift -= ByteShift;
- ByteMask <<= ByteShift;
- ByteMask &= (~0U >> (32-ByteValues.size()));
- }
-
- if (OverallLeftShift >= (int)ByteValues.size()) return true;
- if (OverallLeftShift <= -(int)ByteValues.size()) return true;
-
- return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
- ByteValues);
- }
-
- // If this is a logical 'and' with a mask that clears bytes, clear the
- // corresponding bytes in ByteMask.
- if (I->getOpcode() == Instruction::And &&
- isa<ConstantInt>(I->getOperand(1))) {
- // Scan every byte of the and mask, seeing if the byte is either 0 or 255.
- unsigned NumBytes = ByteValues.size();
- APInt Byte(I->getType()->getPrimitiveSizeInBits(), 255);
- const APInt &AndMask = cast<ConstantInt>(I->getOperand(1))->getValue();
-
- for (unsigned i = 0; i != NumBytes; ++i, Byte <<= 8) {
- // If this byte is masked out by a later operation, we don't care what
- // the and mask is.
- if ((ByteMask & (1 << i)) == 0)
- continue;
-
- // If the AndMask is all zeros for this byte, clear the bit.
- APInt MaskB = AndMask & Byte;
- if (MaskB == 0) {
- ByteMask &= ~(1U << i);
- continue;
- }
-
- // If the AndMask is not all ones for this byte, it's not a bytezap.
- if (MaskB != Byte)
- return true;
-
- // Otherwise, this byte is kept.
- }
-
- return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
- ByteValues);
- }
- }
-
- // Okay, we got to something that isn't a shift, 'or' or 'and'. This must be
- // the input value to the bswap. Some observations: 1) if more than one byte
- // is demanded from this input, then it could not be successfully assembled
- // into a byteswap. At least one of the two bytes would not be aligned with
- // their ultimate destination.
- if (!isPowerOf2_32(ByteMask)) return true;
- unsigned InputByteNo = CountTrailingZeros_32(ByteMask);
-
- // 2) The input and ultimate destinations must line up: if byte 3 of an i32
- // is demanded, it needs to go into byte 0 of the result. This means that the
- // byte needs to be shifted until it lands in the right byte bucket. The
- // shift amount depends on the position: if the byte is coming from the high
- // part of the value (e.g. byte 3) then it must be shifted right. If from the
- // low part, it must be shifted left.
- unsigned DestByteNo = InputByteNo + OverallLeftShift;
- if (InputByteNo < ByteValues.size()/2) {
- if (ByteValues.size()-1-DestByteNo != InputByteNo)
- return true;
- } else {
- if (ByteValues.size()-1-DestByteNo != InputByteNo)
- return true;
- }
-
- // If the destination byte value is already defined, the values are or'd
- // together, which isn't a bswap (unless it's an or of the same bits).
- if (ByteValues[DestByteNo] && ByteValues[DestByteNo] != V)
- return true;
- ByteValues[DestByteNo] = V;
- return false;
-}
-
-/// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom.
-/// If so, insert the new bswap intrinsic and return it.
-Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
- const IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
- if (!ITy || ITy->getBitWidth() % 16 ||
- // ByteMask only allows up to 32-byte values.
- ITy->getBitWidth() > 32*8)
- return 0; // Can only bswap pairs of bytes. Can't do vectors.
-
- /// ByteValues - For each byte of the result, we keep track of which value
- /// defines each byte.
- SmallVector<Value*, 8> ByteValues;
- ByteValues.resize(ITy->getBitWidth()/8);
-
- // Try to find all the pieces corresponding to the bswap.
- uint32_t ByteMask = ~0U >> (32-ByteValues.size());
- if (CollectBSwapParts(&I, 0, ByteMask, ByteValues))
- return 0;
-
- // Check to see if all of the bytes come from the same value.
- Value *V = ByteValues[0];
- if (V == 0) return 0; // Didn't find a byte? Must be zero.
-
- // Check to make sure that all of the bytes come from the same value.
- for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
- if (ByteValues[i] != V)
- return 0;
- const Type *Tys[] = { ITy };
- Module *M = I.getParent()->getParent()->getParent();
- Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1);
- return CallInst::Create(F, V);
-}
-
-/// MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D). Check
-/// If A is (cond?-1:0) and either B or D is ~(cond?-1,0) or (cond?0,-1), then
-/// we can simplify this expression to "cond ? C : D or B".
-static Instruction *MatchSelectFromAndOr(Value *A, Value *B,
- Value *C, Value *D,
- LLVMContext *Context) {
- // If A is not a select of -1/0, this cannot match.
- Value *Cond = 0;
- if (!match(A, m_SelectCst<-1, 0>(m_Value(Cond))))
- return 0;
-
- // ((cond?-1:0)&C) | (B&(cond?0:-1)) -> cond ? C : B.
- if (match(D, m_SelectCst<0, -1>(m_Specific(Cond))))
- return SelectInst::Create(Cond, C, B);
- if (match(D, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond)))))
- return SelectInst::Create(Cond, C, B);
- // ((cond?-1:0)&C) | ((cond?0:-1)&D) -> cond ? C : D.
- if (match(B, m_SelectCst<0, -1>(m_Specific(Cond))))
- return SelectInst::Create(Cond, C, D);
- if (match(B, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond)))))
- return SelectInst::Create(Cond, C, D);
- return 0;
-}
-
-/// FoldOrOfICmps - Fold (icmp)|(icmp) if possible.
-Instruction *InstCombiner::FoldOrOfICmps(Instruction &I,
- ICmpInst *LHS, ICmpInst *RHS) {
- Value *Val, *Val2;
- ConstantInt *LHSCst, *RHSCst;
- ICmpInst::Predicate LHSCC, RHSCC;
-
- // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2).
- if (!match(LHS, m_ICmp(LHSCC, m_Value(Val), m_ConstantInt(LHSCst))) ||
- !match(RHS, m_ICmp(RHSCC, m_Value(Val2), m_ConstantInt(RHSCst))))
- return 0;
-
-
- // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0)
- if (LHSCst == RHSCst && LHSCC == RHSCC &&
- LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) {
- Value *NewOr = Builder->CreateOr(Val, Val2);
- return new ICmpInst(LHSCC, NewOr, LHSCst);
- }
-
- // From here on, we only handle:
- // (icmp1 A, C1) | (icmp2 A, C2) --> something simpler.
- if (Val != Val2) return 0;
-
- // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
- if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
- RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
- LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
- RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
- return 0;
-
- // We can't fold (ugt x, C) | (sgt x, C2).
- if (!PredicatesFoldable(LHSCC, RHSCC))
- return 0;
-
- // Ensure that the larger constant is on the RHS.
- bool ShouldSwap;
- if (CmpInst::isSigned(LHSCC) ||
- (ICmpInst::isEquality(LHSCC) &&
- CmpInst::isSigned(RHSCC)))
- ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
- else
- ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
-
- if (ShouldSwap) {
- std::swap(LHS, RHS);
- std::swap(LHSCst, RHSCst);
- std::swap(LHSCC, RHSCC);
- }
-
- // At this point, we know we have have two icmp instructions
- // comparing a value against two constants and or'ing the result
- // together. Because of the above check, we know that we only have
- // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
- // FoldICmpLogical check above), that the two constants are not
- // equal.
- assert(LHSCst != RHSCst && "Compares not folded above?");
-
- switch (LHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ:
- switch (RHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ:
- if (LHSCst == SubOne(RHSCst)) {
- // (X == 13 | X == 14) -> X-13 <u 2
- Constant *AddCST = ConstantExpr::getNeg(LHSCst);
- Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
- AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
- return new ICmpInst(ICmpInst::ICMP_ULT, Add, AddCST);
- }
- break; // (X == 13 | X == 15) -> no change
- case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
- case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
- break;
- case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15
- case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15
- case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15
- return ReplaceInstUsesWith(I, RHS);
- }
- break;
- case ICmpInst::ICMP_NE:
- switch (RHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13
- case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13
- case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13
- return ReplaceInstUsesWith(I, LHS);
- case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true
- case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true
- case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- }
- break;
- case ICmpInst::ICMP_ULT:
- switch (RHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
- break;
- case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2
- // If RHSCst is [us]MAXINT, it is always false. Not handling
- // this can cause overflow.
- if (RHSCst->isMaxValue(false))
- return ReplaceInstUsesWith(I, LHS);
- return InsertRangeTest(Val, LHSCst, AddOne(RHSCst),
- false, false, I);
- case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change
- break;
- case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15
- case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15
- return ReplaceInstUsesWith(I, RHS);
- case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change
- break;
- }
- break;
- case ICmpInst::ICMP_SLT:
- switch (RHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
- break;
- case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2
- // If RHSCst is [us]MAXINT, it is always false. Not handling
- // this can cause overflow.
- if (RHSCst->isMaxValue(true))
- return ReplaceInstUsesWith(I, LHS);
- return InsertRangeTest(Val, LHSCst, AddOne(RHSCst),
- true, false, I);
- case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change
- break;
- case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15
- case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15
- return ReplaceInstUsesWith(I, RHS);
- case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change
- break;
- }
- break;
- case ICmpInst::ICMP_UGT:
- switch (RHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13
- case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13
- return ReplaceInstUsesWith(I, LHS);
- case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change
- break;
- case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true
- case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change
- break;
- }
- break;
- case ICmpInst::ICMP_SGT:
- switch (RHSCC) {
- default: llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13
- case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13
- return ReplaceInstUsesWith(I, LHS);
- case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change
- break;
- case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true
- case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change
- break;
- }
- break;
- }
- return 0;
-}
-
-Instruction *InstCombiner::FoldOrOfFCmps(Instruction &I, FCmpInst *LHS,
- FCmpInst *RHS) {
- if (LHS->getPredicate() == FCmpInst::FCMP_UNO &&
- RHS->getPredicate() == FCmpInst::FCMP_UNO &&
- LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) {
- if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
- if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
- // If either of the constants are nans, then the whole thing returns
- // true.
- if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
-
- // Otherwise, no need to compare the two constants, compare the
- // rest.
- return new FCmpInst(FCmpInst::FCMP_UNO,
- LHS->getOperand(0), RHS->getOperand(0));
- }
-
- // Handle vector zeros. This occurs because the canonical form of
- // "fcmp uno x,x" is "fcmp uno x, 0".
- if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
- isa<ConstantAggregateZero>(RHS->getOperand(1)))
- return new FCmpInst(FCmpInst::FCMP_UNO,
- LHS->getOperand(0), RHS->getOperand(0));
-
- return 0;
- }
-
- Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
- Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
- FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
-
- if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
- // Swap RHS operands to match LHS.
- Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
- std::swap(Op1LHS, Op1RHS);
- }
- if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
- // Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y).
- if (Op0CC == Op1CC)
- return new FCmpInst((FCmpInst::Predicate)Op0CC,
- Op0LHS, Op0RHS);
- if (Op0CC == FCmpInst::FCMP_TRUE || Op1CC == FCmpInst::FCMP_TRUE)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- if (Op0CC == FCmpInst::FCMP_FALSE)
- return ReplaceInstUsesWith(I, RHS);
- if (Op1CC == FCmpInst::FCMP_FALSE)
- return ReplaceInstUsesWith(I, LHS);
- bool Op0Ordered;
- bool Op1Ordered;
- unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
- unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
- if (Op0Ordered == Op1Ordered) {
- // If both are ordered or unordered, return a new fcmp with
- // or'ed predicates.
- Value *RV = getFCmpValue(Op0Ordered, Op0Pred|Op1Pred,
- Op0LHS, Op0RHS, Context);
- if (Instruction *I = dyn_cast<Instruction>(RV))
- return I;
- // Otherwise, it's a constant boolean value...
- return ReplaceInstUsesWith(I, RV);
- }
- }
- return 0;
-}
-
-/// FoldOrWithConstants - This helper function folds:
-///
-/// ((A | B) & C1) | (B & C2)
-///
-/// into:
-///
-/// (A & C1) | B
-///
-/// when the XOR of the two constants is "all ones" (-1).
-Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op,
- Value *A, Value *B, Value *C) {
- ConstantInt *CI1 = dyn_cast<ConstantInt>(C);
- if (!CI1) return 0;
-
- Value *V1 = 0;
- ConstantInt *CI2 = 0;
- if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return 0;
-
- APInt Xor = CI1->getValue() ^ CI2->getValue();
- if (!Xor.isAllOnesValue()) return 0;
-
- if (V1 == A || V1 == B) {
- Value *NewOp = Builder->CreateAnd((V1 == A) ? B : A, CI1);
- return BinaryOperator::CreateOr(NewOp, V1);
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitOr(BinaryOperator &I) {
- bool Changed = SimplifyCommutative(I);
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (Value *V = SimplifyOrInst(Op0, Op1, TD))
- return ReplaceInstUsesWith(I, V);
-
-
- // See if we can simplify any instructions used by the instruction whose sole
- // purpose is to compute bits we don't care about.
- if (SimplifyDemandedInstructionBits(I))
- return &I;
-
- if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
- ConstantInt *C1 = 0; Value *X = 0;
- // (X & C1) | C2 --> (X | C2) & (C1|C2)
- if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) &&
- isOnlyUse(Op0)) {
- Value *Or = Builder->CreateOr(X, RHS);
- Or->takeName(Op0);
- return BinaryOperator::CreateAnd(Or,
- ConstantInt::get(*Context, RHS->getValue() | C1->getValue()));
- }
-
- // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
- if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) &&
- isOnlyUse(Op0)) {
- Value *Or = Builder->CreateOr(X, RHS);
- Or->takeName(Op0);
- return BinaryOperator::CreateXor(Or,
- ConstantInt::get(*Context, C1->getValue() & ~RHS->getValue()));
- }
-
- // Try to fold constant and into select arguments.
- if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
- if (Instruction *R = FoldOpIntoSelect(I, SI, this))
- return R;
- if (isa<PHINode>(Op0))
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
- }
-
- Value *A = 0, *B = 0;
- ConstantInt *C1 = 0, *C2 = 0;
-
- // (A | B) | C and A | (B | C) -> bswap if possible.
- // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
- if (match(Op0, m_Or(m_Value(), m_Value())) ||
- match(Op1, m_Or(m_Value(), m_Value())) ||
- (match(Op0, m_Shift(m_Value(), m_Value())) &&
- match(Op1, m_Shift(m_Value(), m_Value())))) {
- if (Instruction *BSwap = MatchBSwap(I))
- return BSwap;
- }
-
- // (X^C)|Y -> (X|Y)^C iff Y&C == 0
- if (Op0->hasOneUse() &&
- match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
- MaskedValueIsZero(Op1, C1->getValue())) {
- Value *NOr = Builder->CreateOr(A, Op1);
- NOr->takeName(Op0);
- return BinaryOperator::CreateXor(NOr, C1);
- }
-
- // Y|(X^C) -> (X|Y)^C iff Y&C == 0
- if (Op1->hasOneUse() &&
- match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
- MaskedValueIsZero(Op0, C1->getValue())) {
- Value *NOr = Builder->CreateOr(A, Op0);
- NOr->takeName(Op0);
- return BinaryOperator::CreateXor(NOr, C1);
- }
-
- // (A & C)|(B & D)
- Value *C = 0, *D = 0;
- if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
- match(Op1, m_And(m_Value(B), m_Value(D)))) {
- Value *V1 = 0, *V2 = 0, *V3 = 0;
- C1 = dyn_cast<ConstantInt>(C);
- C2 = dyn_cast<ConstantInt>(D);
- if (C1 && C2) { // (A & C1)|(B & C2)
- // If we have: ((V + N) & C1) | (V & C2)
- // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
- // replace with V+N.
- if (C1->getValue() == ~C2->getValue()) {
- if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+
- match(A, m_Add(m_Value(V1), m_Value(V2)))) {
- // Add commutes, try both ways.
- if (V1 == B && MaskedValueIsZero(V2, C2->getValue()))
- return ReplaceInstUsesWith(I, A);
- if (V2 == B && MaskedValueIsZero(V1, C2->getValue()))
- return ReplaceInstUsesWith(I, A);
- }
- // Or commutes, try both ways.
- if ((C1->getValue() & (C1->getValue()+1)) == 0 &&
- match(B, m_Add(m_Value(V1), m_Value(V2)))) {
- // Add commutes, try both ways.
- if (V1 == A && MaskedValueIsZero(V2, C1->getValue()))
- return ReplaceInstUsesWith(I, B);
- if (V2 == A && MaskedValueIsZero(V1, C1->getValue()))
- return ReplaceInstUsesWith(I, B);
- }
- }
-
- // ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2)
- // iff (C1&C2) == 0 and (N&~C1) == 0
- if ((C1->getValue() & C2->getValue()) == 0) {
- if (match(A, m_Or(m_Value(V1), m_Value(V2))) &&
- ((V1 == B && MaskedValueIsZero(V2, ~C1->getValue())) || // (V|N)
- (V2 == B && MaskedValueIsZero(V1, ~C1->getValue())))) // (N|V)
- return BinaryOperator::CreateAnd(A,
- ConstantInt::get(A->getContext(),
- C1->getValue()|C2->getValue()));
- // Or commutes, try both ways.
- if (match(B, m_Or(m_Value(V1), m_Value(V2))) &&
- ((V1 == A && MaskedValueIsZero(V2, ~C2->getValue())) || // (V|N)
- (V2 == A && MaskedValueIsZero(V1, ~C2->getValue())))) // (N|V)
- return BinaryOperator::CreateAnd(B,
- ConstantInt::get(B->getContext(),
- C1->getValue()|C2->getValue()));
- }
- }
-
- // Check to see if we have any common things being and'ed. If so, find the
- // terms for V1 & (V2|V3).
- if (isOnlyUse(Op0) || isOnlyUse(Op1)) {
- V1 = 0;
- if (A == B) // (A & C)|(A & D) == A & (C|D)
- V1 = A, V2 = C, V3 = D;
- else if (A == D) // (A & C)|(B & A) == A & (B|C)
- V1 = A, V2 = B, V3 = C;
- else if (C == B) // (A & C)|(C & D) == C & (A|D)
- V1 = C, V2 = A, V3 = D;
- else if (C == D) // (A & C)|(B & C) == C & (A|B)
- V1 = C, V2 = A, V3 = B;
-
- if (V1) {
- Value *Or = Builder->CreateOr(V2, V3, "tmp");
- return BinaryOperator::CreateAnd(V1, Or);
- }
- }
-
- // (A & (C0?-1:0)) | (B & ~(C0?-1:0)) -> C0 ? A : B, and commuted variants
- if (Instruction *Match = MatchSelectFromAndOr(A, B, C, D, Context))
- return Match;
- if (Instruction *Match = MatchSelectFromAndOr(B, A, D, C, Context))
- return Match;
- if (Instruction *Match = MatchSelectFromAndOr(C, B, A, D, Context))
- return Match;
- if (Instruction *Match = MatchSelectFromAndOr(D, A, B, C, Context))
- return Match;
-
- // ((A&~B)|(~A&B)) -> A^B
- if ((match(C, m_Not(m_Specific(D))) &&
- match(B, m_Not(m_Specific(A)))))
- return BinaryOperator::CreateXor(A, D);
- // ((~B&A)|(~A&B)) -> A^B
- if ((match(A, m_Not(m_Specific(D))) &&
- match(B, m_Not(m_Specific(C)))))
- return BinaryOperator::CreateXor(C, D);
- // ((A&~B)|(B&~A)) -> A^B
- if ((match(C, m_Not(m_Specific(B))) &&
- match(D, m_Not(m_Specific(A)))))
- return BinaryOperator::CreateXor(A, B);
- // ((~B&A)|(B&~A)) -> A^B
- if ((match(A, m_Not(m_Specific(B))) &&
- match(D, m_Not(m_Specific(C)))))
- return BinaryOperator::CreateXor(C, B);
- }
-
- // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
- if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
- if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
- if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
- SI0->getOperand(1) == SI1->getOperand(1) &&
- (SI0->hasOneUse() || SI1->hasOneUse())) {
- Value *NewOp = Builder->CreateOr(SI0->getOperand(0), SI1->getOperand(0),
- SI0->getName());
- return BinaryOperator::Create(SI1->getOpcode(), NewOp,
- SI1->getOperand(1));
- }
- }
-
- // ((A|B)&1)|(B&-2) -> (A&1) | B
- if (match(Op0, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
- match(Op0, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
- Instruction *Ret = FoldOrWithConstants(I, Op1, A, B, C);
- if (Ret) return Ret;
- }
- // (B&-2)|((A|B)&1) -> (A&1) | B
- if (match(Op1, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
- match(Op1, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
- Instruction *Ret = FoldOrWithConstants(I, Op0, A, B, C);
- if (Ret) return Ret;
- }
-
- // (~A | ~B) == (~(A & B)) - De Morgan's Law
- if (Value *Op0NotVal = dyn_castNotVal(Op0))
- if (Value *Op1NotVal = dyn_castNotVal(Op1))
- if (Op0->hasOneUse() && Op1->hasOneUse()) {
- Value *And = Builder->CreateAnd(Op0NotVal, Op1NotVal,
- I.getName()+".demorgan");
- return BinaryOperator::CreateNot(And);
- }
-
- // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
- if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) {
- if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
- return R;
-
- if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
- if (Instruction *Res = FoldOrOfICmps(I, LHS, RHS))
- return Res;
- }
-
- // fold (or (cast A), (cast B)) -> (cast (or A, B))
- if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
- if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
- if (Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
- if (!isa<ICmpInst>(Op0C->getOperand(0)) ||
- !isa<ICmpInst>(Op1C->getOperand(0))) {
- const Type *SrcTy = Op0C->getOperand(0)->getType();
- if (SrcTy == Op1C->getOperand(0)->getType() &&
- SrcTy->isIntOrIntVector() &&
- // Only do this if the casts both really cause code to be
- // generated.
- ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
- I.getType(), TD) &&
- ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
- I.getType(), TD)) {
- Value *NewOp = Builder->CreateOr(Op0C->getOperand(0),
- Op1C->getOperand(0), I.getName());
- return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
- }
- }
- }
- }
-
-
- // (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y)
- if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
- if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
- if (Instruction *Res = FoldOrOfFCmps(I, LHS, RHS))
- return Res;
- }
-
- return Changed ? &I : 0;
-}
-
-namespace {
-
-// XorSelf - Implements: X ^ X --> 0
-struct XorSelf {
- Value *RHS;
- XorSelf(Value *rhs) : RHS(rhs) {}
- bool shouldApply(Value *LHS) const { return LHS == RHS; }
- Instruction *apply(BinaryOperator &Xor) const {
- return &Xor;
- }
-};
-
-}
-
-Instruction *InstCombiner::visitXor(BinaryOperator &I) {
- bool Changed = SimplifyCommutative(I);
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (isa<UndefValue>(Op1)) {
- if (isa<UndefValue>(Op0))
- // Handle undef ^ undef -> 0 special case. This is a common
- // idiom (misuse).
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
- return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
- }
-
- // xor X, X = 0, even if X is nested in a sequence of Xor's.
- if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
- assert(Result == &I && "AssociativeOpt didn't work?"); Result=Result;
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
- }
-
- // See if we can simplify any instructions used by the instruction whose sole
- // purpose is to compute bits we don't care about.
- if (SimplifyDemandedInstructionBits(I))
- return &I;
- if (isa<VectorType>(I.getType()))
- if (isa<ConstantAggregateZero>(Op1))
- return ReplaceInstUsesWith(I, Op0); // X ^ <0,0> -> X
-
- // Is this a ~ operation?
- if (Value *NotOp = dyn_castNotVal(&I)) {
- if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) {
- if (Op0I->getOpcode() == Instruction::And ||
- Op0I->getOpcode() == Instruction::Or) {
- // ~(~X & Y) --> (X | ~Y) - De Morgan's Law
- // ~(~X | Y) === (X & ~Y) - De Morgan's Law
- if (dyn_castNotVal(Op0I->getOperand(1)))
- Op0I->swapOperands();
- if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
- Value *NotY =
- Builder->CreateNot(Op0I->getOperand(1),
- Op0I->getOperand(1)->getName()+".not");
- if (Op0I->getOpcode() == Instruction::And)
- return BinaryOperator::CreateOr(Op0NotVal, NotY);
- return BinaryOperator::CreateAnd(Op0NotVal, NotY);
- }
-
- // ~(X & Y) --> (~X | ~Y) - De Morgan's Law
- // ~(X | Y) === (~X & ~Y) - De Morgan's Law
- if (isFreeToInvert(Op0I->getOperand(0)) &&
- isFreeToInvert(Op0I->getOperand(1))) {
- Value *NotX =
- Builder->CreateNot(Op0I->getOperand(0), "notlhs");
- Value *NotY =
- Builder->CreateNot(Op0I->getOperand(1), "notrhs");
- if (Op0I->getOpcode() == Instruction::And)
- return BinaryOperator::CreateOr(NotX, NotY);
- return BinaryOperator::CreateAnd(NotX, NotY);
- }
- }
- }
- }
-
-
- if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
- if (RHS->isOne() && Op0->hasOneUse()) {
- // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
- if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
- return new ICmpInst(ICI->getInversePredicate(),
- ICI->getOperand(0), ICI->getOperand(1));
-
- if (FCmpInst *FCI = dyn_cast<FCmpInst>(Op0))
- return new FCmpInst(FCI->getInversePredicate(),
- FCI->getOperand(0), FCI->getOperand(1));
- }
-
- // fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp).
- if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
- if (CmpInst *CI = dyn_cast<CmpInst>(Op0C->getOperand(0))) {
- if (CI->hasOneUse() && Op0C->hasOneUse()) {
- Instruction::CastOps Opcode = Op0C->getOpcode();
- if ((Opcode == Instruction::ZExt || Opcode == Instruction::SExt) &&
- (RHS == ConstantExpr::getCast(Opcode,
- ConstantInt::getTrue(*Context),
- Op0C->getDestTy()))) {
- CI->setPredicate(CI->getInversePredicate());
- return CastInst::Create(Opcode, CI, Op0C->getType());
- }
- }
- }
- }
-
- if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
- // ~(c-X) == X-c-1 == X+(-c-1)
- if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
- if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
- Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
- Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
- ConstantInt::get(I.getType(), 1));
- return BinaryOperator::CreateAdd(Op0I->getOperand(1), ConstantRHS);
- }
-
- if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
- if (Op0I->getOpcode() == Instruction::Add) {
- // ~(X-c) --> (-c-1)-X
- if (RHS->isAllOnesValue()) {
- Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
- return BinaryOperator::CreateSub(
- ConstantExpr::getSub(NegOp0CI,
- ConstantInt::get(I.getType(), 1)),
- Op0I->getOperand(0));
- } else if (RHS->getValue().isSignBit()) {
- // (X + C) ^ signbit -> (X + C + signbit)
- Constant *C = ConstantInt::get(*Context,
- RHS->getValue() + Op0CI->getValue());
- return BinaryOperator::CreateAdd(Op0I->getOperand(0), C);
-
- }
- } else if (Op0I->getOpcode() == Instruction::Or) {
- // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
- if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) {
- Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
- // Anything in both C1 and C2 is known to be zero, remove it from
- // NewRHS.
- Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHS);
- NewRHS = ConstantExpr::getAnd(NewRHS,
- ConstantExpr::getNot(CommonBits));
- Worklist.Add(Op0I);
- I.setOperand(0, Op0I->getOperand(0));
- I.setOperand(1, NewRHS);
- return &I;
- }
- }
- }
- }
-
- // Try to fold constant and into select arguments.
- if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
- if (Instruction *R = FoldOpIntoSelect(I, SI, this))
- return R;
- if (isa<PHINode>(Op0))
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
- }
-
- if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
- if (X == Op1)
- return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
-
- if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
- if (X == Op0)
- return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
-
-
- BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
- if (Op1I) {
- Value *A, *B;
- if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
- if (A == Op0) { // B^(B|A) == (A|B)^B
- Op1I->swapOperands();
- I.swapOperands();
- std::swap(Op0, Op1);
- } else if (B == Op0) { // B^(A|B) == (A|B)^B
- I.swapOperands(); // Simplified below.
- std::swap(Op0, Op1);
- }
- } else if (match(Op1I, m_Xor(m_Specific(Op0), m_Value(B)))) {
- return ReplaceInstUsesWith(I, B); // A^(A^B) == B
- } else if (match(Op1I, m_Xor(m_Value(A), m_Specific(Op0)))) {
- return ReplaceInstUsesWith(I, A); // A^(B^A) == B
- } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) &&
- Op1I->hasOneUse()){
- if (A == Op0) { // A^(A&B) -> A^(B&A)
- Op1I->swapOperands();
- std::swap(A, B);
- }
- if (B == Op0) { // A^(B&A) -> (B&A)^A
- I.swapOperands(); // Simplified below.
- std::swap(Op0, Op1);
- }
- }
- }
-
- BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
- if (Op0I) {
- Value *A, *B;
- if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
- Op0I->hasOneUse()) {
- if (A == Op1) // (B|A)^B == (A|B)^B
- std::swap(A, B);
- if (B == Op1) // (A|B)^B == A & ~B
- return BinaryOperator::CreateAnd(A, Builder->CreateNot(Op1, "tmp"));
- } else if (match(Op0I, m_Xor(m_Specific(Op1), m_Value(B)))) {
- return ReplaceInstUsesWith(I, B); // (A^B)^A == B
- } else if (match(Op0I, m_Xor(m_Value(A), m_Specific(Op1)))) {
- return ReplaceInstUsesWith(I, A); // (B^A)^A == B
- } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
- Op0I->hasOneUse()){
- if (A == Op1) // (A&B)^A -> (B&A)^A
- std::swap(A, B);
- if (B == Op1 && // (B&A)^A == ~B & A
- !isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C
- return BinaryOperator::CreateAnd(Builder->CreateNot(A, "tmp"), Op1);
- }
- }
- }
-
- // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
- if (Op0I && Op1I && Op0I->isShift() &&
- Op0I->getOpcode() == Op1I->getOpcode() &&
- Op0I->getOperand(1) == Op1I->getOperand(1) &&
- (Op1I->hasOneUse() || Op1I->hasOneUse())) {
- Value *NewOp =
- Builder->CreateXor(Op0I->getOperand(0), Op1I->getOperand(0),
- Op0I->getName());
- return BinaryOperator::Create(Op1I->getOpcode(), NewOp,
- Op1I->getOperand(1));
- }
-
- if (Op0I && Op1I) {
- Value *A, *B, *C, *D;
- // (A & B)^(A | B) -> A ^ B
- if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
- match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
- if ((A == C && B == D) || (A == D && B == C))
- return BinaryOperator::CreateXor(A, B);
- }
- // (A | B)^(A & B) -> A ^ B
- if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
- match(Op1I, m_And(m_Value(C), m_Value(D)))) {
- if ((A == C && B == D) || (A == D && B == C))
- return BinaryOperator::CreateXor(A, B);
- }
-
- // (A & B)^(C & D)
- if ((Op0I->hasOneUse() || Op1I->hasOneUse()) &&
- match(Op0I, m_And(m_Value(A), m_Value(B))) &&
- match(Op1I, m_And(m_Value(C), m_Value(D)))) {
- // (X & Y)^(X & Y) -> (Y^Z) & X
- Value *X = 0, *Y = 0, *Z = 0;
- if (A == C)
- X = A, Y = B, Z = D;
- else if (A == D)
- X = A, Y = B, Z = C;
- else if (B == C)
- X = B, Y = A, Z = D;
- else if (B == D)
- X = B, Y = A, Z = C;
-
- if (X) {
- Value *NewOp = Builder->CreateXor(Y, Z, Op0->getName());
- return BinaryOperator::CreateAnd(NewOp, X);
- }
- }
- }
-
- // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
- if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
- if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
- return R;
-
- // fold (xor (cast A), (cast B)) -> (cast (xor A, B))
- if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
- if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
- if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
- const Type *SrcTy = Op0C->getOperand(0)->getType();
- if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
- // Only do this if the casts both really cause code to be generated.
- ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
- I.getType(), TD) &&
- ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
- I.getType(), TD)) {
- Value *NewOp = Builder->CreateXor(Op0C->getOperand(0),
- Op1C->getOperand(0), I.getName());
- return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
- }
- }
- }
-
- return Changed ? &I : 0;
-}
-
-static ConstantInt *ExtractElement(Constant *V, Constant *Idx,
- LLVMContext *Context) {
- return cast<ConstantInt>(ConstantExpr::getExtractElement(V, Idx));
-}
-
-static bool HasAddOverflow(ConstantInt *Result,
- ConstantInt *In1, ConstantInt *In2,
- bool IsSigned) {
- if (IsSigned)
- if (In2->getValue().isNegative())
- return Result->getValue().sgt(In1->getValue());
- else
- return Result->getValue().slt(In1->getValue());
- else
- return Result->getValue().ult(In1->getValue());
-}
-
-/// AddWithOverflow - Compute Result = In1+In2, returning true if the result
-/// overflowed for this type.
-static bool AddWithOverflow(Constant *&Result, Constant *In1,
- Constant *In2, LLVMContext *Context,
- bool IsSigned = false) {
- Result = ConstantExpr::getAdd(In1, In2);
-
- if (const VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
- for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
- Constant *Idx = ConstantInt::get(Type::getInt32Ty(*Context), i);
- if (HasAddOverflow(ExtractElement(Result, Idx, Context),
- ExtractElement(In1, Idx, Context),
- ExtractElement(In2, Idx, Context),
- IsSigned))
- return true;
- }
- return false;
- }
-
- return HasAddOverflow(cast<ConstantInt>(Result),
- cast<ConstantInt>(In1), cast<ConstantInt>(In2),
- IsSigned);
-}
-
-static bool HasSubOverflow(ConstantInt *Result,
- ConstantInt *In1, ConstantInt *In2,
- bool IsSigned) {
- if (IsSigned)
- if (In2->getValue().isNegative())
- return Result->getValue().slt(In1->getValue());
- else
- return Result->getValue().sgt(In1->getValue());
- else
- return Result->getValue().ugt(In1->getValue());
-}
-
-/// SubWithOverflow - Compute Result = In1-In2, returning true if the result
-/// overflowed for this type.
-static bool SubWithOverflow(Constant *&Result, Constant *In1,
- Constant *In2, LLVMContext *Context,
- bool IsSigned = false) {
- Result = ConstantExpr::getSub(In1, In2);
-
- if (const VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
- for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
- Constant *Idx = ConstantInt::get(Type::getInt32Ty(*Context), i);
- if (HasSubOverflow(ExtractElement(Result, Idx, Context),
- ExtractElement(In1, Idx, Context),
- ExtractElement(In2, Idx, Context),
- IsSigned))
- return true;
- }
- return false;
- }
-
- return HasSubOverflow(cast<ConstantInt>(Result),
- cast<ConstantInt>(In1), cast<ConstantInt>(In2),
- IsSigned);
-}
-
-
-/// FoldGEPICmp - Fold comparisons between a GEP instruction and something
-/// else. At this point we know that the GEP is on the LHS of the comparison.
-Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
- ICmpInst::Predicate Cond,
- Instruction &I) {
- // Look through bitcasts.
- if (BitCastInst *BCI = dyn_cast<BitCastInst>(RHS))
- RHS = BCI->getOperand(0);
-
- Value *PtrBase = GEPLHS->getOperand(0);
- if (TD && PtrBase == RHS && GEPLHS->isInBounds()) {
- // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
- // This transformation (ignoring the base and scales) is valid because we
- // know pointers can't overflow since the gep is inbounds. See if we can
- // output an optimized form.
- Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, I, *this);
-
- // If not, synthesize the offset the hard way.
- if (Offset == 0)
- Offset = EmitGEPOffset(GEPLHS, *this);
- return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
- Constant::getNullValue(Offset->getType()));
- } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
- // If the base pointers are different, but the indices are the same, just
- // compare the base pointer.
- if (PtrBase != GEPRHS->getOperand(0)) {
- bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
- IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
- GEPRHS->getOperand(0)->getType();
- if (IndicesTheSame)
- for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
- if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
- IndicesTheSame = false;
- break;
- }
-
- // If all indices are the same, just compare the base pointers.
- if (IndicesTheSame)
- return new ICmpInst(ICmpInst::getSignedPredicate(Cond),
- GEPLHS->getOperand(0), GEPRHS->getOperand(0));
-
- // Otherwise, the base pointers are different and the indices are
- // different, bail out.
- return 0;
- }
-
- // If one of the GEPs has all zero indices, recurse.
- bool AllZeros = true;
- for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
- if (!isa<Constant>(GEPLHS->getOperand(i)) ||
- !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
- AllZeros = false;
- break;
- }
- if (AllZeros)
- return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
- ICmpInst::getSwappedPredicate(Cond), I);
-
- // If the other GEP has all zero indices, recurse.
- AllZeros = true;
- for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
- if (!isa<Constant>(GEPRHS->getOperand(i)) ||
- !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
- AllZeros = false;
- break;
- }
- if (AllZeros)
- return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
-
- if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
- // If the GEPs only differ by one index, compare it.
- unsigned NumDifferences = 0; // Keep track of # differences.
- unsigned DiffOperand = 0; // The operand that differs.
- for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
- if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
- if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
- GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
- // Irreconcilable differences.
- NumDifferences = 2;
- break;
- } else {
- if (NumDifferences++) break;
- DiffOperand = i;
- }
- }
-
- if (NumDifferences == 0) // SAME GEP?
- return ReplaceInstUsesWith(I, // No comparison is needed here.
- ConstantInt::get(Type::getInt1Ty(*Context),
- ICmpInst::isTrueWhenEqual(Cond)));
-
- else if (NumDifferences == 1) {
- Value *LHSV = GEPLHS->getOperand(DiffOperand);
- Value *RHSV = GEPRHS->getOperand(DiffOperand);
- // Make sure we do a signed comparison here.
- return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
- }
- }
-
- // Only lower this if the icmp is the only user of the GEP or if we expect
- // the result to fold to a constant!
- if (TD &&
- (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
- (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
- // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
- Value *L = EmitGEPOffset(GEPLHS, *this);
- Value *R = EmitGEPOffset(GEPRHS, *this);
- return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
- }
- }
- return 0;
-}
-
-/// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible.
-///
-Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I,
- Instruction *LHSI,
- Constant *RHSC) {
- if (!isa<ConstantFP>(RHSC)) return 0;
- const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
-
- // Get the width of the mantissa. We don't want to hack on conversions that
- // might lose information from the integer, e.g. "i64 -> float"
- int MantissaWidth = LHSI->getType()->getFPMantissaWidth();
- if (MantissaWidth == -1) return 0; // Unknown.
-
- // Check to see that the input is converted from an integer type that is small
- // enough that preserves all bits. TODO: check here for "known" sign bits.
- // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
- unsigned InputSize = LHSI->getOperand(0)->getType()->getScalarSizeInBits();
-
- // If this is a uitofp instruction, we need an extra bit to hold the sign.
- bool LHSUnsigned = isa<UIToFPInst>(LHSI);
- if (LHSUnsigned)
- ++InputSize;
-
- // If the conversion would lose info, don't hack on this.
- if ((int)InputSize > MantissaWidth)
- return 0;
-
- // Otherwise, we can potentially simplify the comparison. We know that it
- // will always come through as an integer value and we know the constant is
- // not a NAN (it would have been previously simplified).
- assert(!RHS.isNaN() && "NaN comparison not already folded!");
-
- ICmpInst::Predicate Pred;
- switch (I.getPredicate()) {
- default: llvm_unreachable("Unexpected predicate!");
- case FCmpInst::FCMP_UEQ:
- case FCmpInst::FCMP_OEQ:
- Pred = ICmpInst::ICMP_EQ;
- break;
- case FCmpInst::FCMP_UGT:
- case FCmpInst::FCMP_OGT:
- Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT;
- break;
- case FCmpInst::FCMP_UGE:
- case FCmpInst::FCMP_OGE:
- Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
- break;
- case FCmpInst::FCMP_ULT:
- case FCmpInst::FCMP_OLT:
- Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT;
- break;
- case FCmpInst::FCMP_ULE:
- case FCmpInst::FCMP_OLE:
- Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE;
- break;
- case FCmpInst::FCMP_UNE:
- case FCmpInst::FCMP_ONE:
- Pred = ICmpInst::ICMP_NE;
- break;
- case FCmpInst::FCMP_ORD:
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- case FCmpInst::FCMP_UNO:
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- }
-
- const IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType());
-
- // Now we know that the APFloat is a normal number, zero or inf.
-
- // See if the FP constant is too large for the integer. For example,
- // comparing an i8 to 300.0.
- unsigned IntWidth = IntTy->getScalarSizeInBits();
-
- if (!LHSUnsigned) {
- // If the RHS value is > SignedMax, fold the comparison. This handles +INF
- // and large values.
- APFloat SMax(RHS.getSemantics(), APFloat::fcZero, false);
- SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true,
- APFloat::rmNearestTiesToEven);
- if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0
- if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT ||
- Pred == ICmpInst::ICMP_SLE)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- }
- } else {
- // If the RHS value is > UnsignedMax, fold the comparison. This handles
- // +INF and large values.
- APFloat UMax(RHS.getSemantics(), APFloat::fcZero, false);
- UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false,
- APFloat::rmNearestTiesToEven);
- if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0
- if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT ||
- Pred == ICmpInst::ICMP_ULE)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- }
- }
-
- if (!LHSUnsigned) {
- // See if the RHS value is < SignedMin.
- APFloat SMin(RHS.getSemantics(), APFloat::fcZero, false);
- SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true,
- APFloat::rmNearestTiesToEven);
- if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0
- if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT ||
- Pred == ICmpInst::ICMP_SGE)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- }
- }
-
- // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
- // [0, UMAX], but it may still be fractional. See if it is fractional by
- // casting the FP value to the integer value and back, checking for equality.
- // Don't do this for zero, because -0.0 is not fractional.
- Constant *RHSInt = LHSUnsigned
- ? ConstantExpr::getFPToUI(RHSC, IntTy)
- : ConstantExpr::getFPToSI(RHSC, IntTy);
- if (!RHS.isZero()) {
- bool Equal = LHSUnsigned
- ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC
- : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC;
- if (!Equal) {
- // If we had a comparison against a fractional value, we have to adjust
- // the compare predicate and sometimes the value. RHSC is rounded towards
- // zero at this point.
- switch (Pred) {
- default: llvm_unreachable("Unexpected integer comparison!");
- case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- case ICmpInst::ICMP_ULE:
- // (float)int <= 4.4 --> int <= 4
- // (float)int <= -4.4 --> false
- if (RHS.isNegative())
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- break;
- case ICmpInst::ICMP_SLE:
- // (float)int <= 4.4 --> int <= 4
- // (float)int <= -4.4 --> int < -4
- if (RHS.isNegative())
- Pred = ICmpInst::ICMP_SLT;
- break;
- case ICmpInst::ICMP_ULT:
- // (float)int < -4.4 --> false
- // (float)int < 4.4 --> int <= 4
- if (RHS.isNegative())
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- Pred = ICmpInst::ICMP_ULE;
- break;
- case ICmpInst::ICMP_SLT:
- // (float)int < -4.4 --> int < -4
- // (float)int < 4.4 --> int <= 4
- if (!RHS.isNegative())
- Pred = ICmpInst::ICMP_SLE;
- break;
- case ICmpInst::ICMP_UGT:
- // (float)int > 4.4 --> int > 4
- // (float)int > -4.4 --> true
- if (RHS.isNegative())
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- break;
- case ICmpInst::ICMP_SGT:
- // (float)int > 4.4 --> int > 4
- // (float)int > -4.4 --> int >= -4
- if (RHS.isNegative())
- Pred = ICmpInst::ICMP_SGE;
- break;
- case ICmpInst::ICMP_UGE:
- // (float)int >= -4.4 --> true
- // (float)int >= 4.4 --> int > 4
- if (!RHS.isNegative())
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- Pred = ICmpInst::ICMP_UGT;
- break;
- case ICmpInst::ICMP_SGE:
- // (float)int >= -4.4 --> int >= -4
- // (float)int >= 4.4 --> int > 4
- if (!RHS.isNegative())
- Pred = ICmpInst::ICMP_SGT;
- break;
- }
- }
- }
-
- // Lower this FP comparison into an appropriate integer version of the
- // comparison.
- return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt);
-}
-
-/// FoldCmpLoadFromIndexedGlobal - Called we see this pattern:
-/// cmp pred (load (gep GV, ...)), cmpcst
-/// where GV is a global variable with a constant initializer. Try to simplify
-/// this into some simple computation that does not need the load. For example
-/// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3".
-///
-/// If AndCst is non-null, then the loaded value is masked with that constant
-/// before doing the comparison. This handles cases like "A[i]&4 == 0".
-Instruction *InstCombiner::
-FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV,
- CmpInst &ICI, ConstantInt *AndCst) {
- ConstantArray *Init = dyn_cast<ConstantArray>(GV->getInitializer());
- if (Init == 0 || Init->getNumOperands() > 1024) return 0;
-
- // There are many forms of this optimization we can handle, for now, just do
- // the simple index into a single-dimensional array.
- //
- // Require: GEP GV, 0, i {{, constant indices}}
- if (GEP->getNumOperands() < 3 ||
- !isa<ConstantInt>(GEP->getOperand(1)) ||
- !cast<ConstantInt>(GEP->getOperand(1))->isZero() ||
- isa<Constant>(GEP->getOperand(2)))
- return 0;
-
- // Check that indices after the variable are constants and in-range for the
- // type they index. Collect the indices. This is typically for arrays of
- // structs.
- SmallVector<unsigned, 4> LaterIndices;
-
- const Type *EltTy = cast<ArrayType>(Init->getType())->getElementType();
- for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) {
- ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i));
- if (Idx == 0) return 0; // Variable index.
-
- uint64_t IdxVal = Idx->getZExtValue();
- if ((unsigned)IdxVal != IdxVal) return 0; // Too large array index.
-
- if (const StructType *STy = dyn_cast<StructType>(EltTy))
- EltTy = STy->getElementType(IdxVal);
- else if (const ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) {
- if (IdxVal >= ATy->getNumElements()) return 0;
- EltTy = ATy->getElementType();
- } else {
- return 0; // Unknown type.
- }
-
- LaterIndices.push_back(IdxVal);
- }
-
- enum { Overdefined = -3, Undefined = -2 };
-
- // Variables for our state machines.
-
- // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form
- // "i == 47 | i == 87", where 47 is the first index the condition is true for,
- // and 87 is the second (and last) index. FirstTrueElement is -2 when
- // undefined, otherwise set to the first true element. SecondTrueElement is
- // -2 when undefined, -3 when overdefined and >= 0 when that index is true.
- int FirstTrueElement = Undefined, SecondTrueElement = Undefined;
-
- // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the
- // form "i != 47 & i != 87". Same state transitions as for true elements.
- int FirstFalseElement = Undefined, SecondFalseElement = Undefined;
-
- /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these
- /// define a state machine that triggers for ranges of values that the index
- /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'.
- /// This is -2 when undefined, -3 when overdefined, and otherwise the last
- /// index in the range (inclusive). We use -2 for undefined here because we
- /// use relative comparisons and don't want 0-1 to match -1.
- int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined;
-
- // MagicBitvector - This is a magic bitvector where we set a bit if the
- // comparison is true for element 'i'. If there are 64 elements or less in
- // the array, this will fully represent all the comparison results.
- uint64_t MagicBitvector = 0;
-
-
- // Scan the array and see if one of our patterns matches.
- Constant *CompareRHS = cast<Constant>(ICI.getOperand(1));
- for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
- Constant *Elt = Init->getOperand(i);
-
- // If this is indexing an array of structures, get the structure element.
- if (!LaterIndices.empty())
- Elt = ConstantExpr::getExtractValue(Elt, LaterIndices.data(),
- LaterIndices.size());
-
- // If the element is masked, handle it.
- if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst);
-
- // Find out if the comparison would be true or false for the i'th element.
- Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt,
- CompareRHS, TD);
- // If the result is undef for this element, ignore it.
- if (isa<UndefValue>(C)) {
- // Extend range state machines to cover this element in case there is an
- // undef in the middle of the range.
- if (TrueRangeEnd == (int)i-1)
- TrueRangeEnd = i;
- if (FalseRangeEnd == (int)i-1)
- FalseRangeEnd = i;
- continue;
- }
-
- // If we can't compute the result for any of the elements, we have to give
- // up evaluating the entire conditional.
- if (!isa<ConstantInt>(C)) return 0;
-
- // Otherwise, we know if the comparison is true or false for this element,
- // update our state machines.
- bool IsTrueForElt = !cast<ConstantInt>(C)->isZero();
-
- // State machine for single/double/range index comparison.
- if (IsTrueForElt) {
- // Update the TrueElement state machine.
- if (FirstTrueElement == Undefined)
- FirstTrueElement = TrueRangeEnd = i; // First true element.
- else {
- // Update double-compare state machine.
- if (SecondTrueElement == Undefined)
- SecondTrueElement = i;
- else
- SecondTrueElement = Overdefined;
-
- // Update range state machine.
- if (TrueRangeEnd == (int)i-1)
- TrueRangeEnd = i;
- else
- TrueRangeEnd = Overdefined;
- }
- } else {
- // Update the FalseElement state machine.
- if (FirstFalseElement == Undefined)
- FirstFalseElement = FalseRangeEnd = i; // First false element.
- else {
- // Update double-compare state machine.
- if (SecondFalseElement == Undefined)
- SecondFalseElement = i;
- else
- SecondFalseElement = Overdefined;
-
- // Update range state machine.
- if (FalseRangeEnd == (int)i-1)
- FalseRangeEnd = i;
- else
- FalseRangeEnd = Overdefined;
- }
- }
-
-
- // If this element is in range, update our magic bitvector.
- if (i < 64 && IsTrueForElt)
- MagicBitvector |= 1ULL << i;
-
- // If all of our states become overdefined, bail out early. Since the
- // predicate is expensive, only check it every 8 elements. This is only
- // really useful for really huge arrays.
- if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined &&
- SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined &&
- FalseRangeEnd == Overdefined)
- return 0;
- }
-
- // Now that we've scanned the entire array, emit our new comparison(s). We
- // order the state machines in complexity of the generated code.
- Value *Idx = GEP->getOperand(2);
-
-
- // If the comparison is only true for one or two elements, emit direct
- // comparisons.
- if (SecondTrueElement != Overdefined) {
- // None true -> false.
- if (FirstTrueElement == Undefined)
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
-
- Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement);
-
- // True for one element -> 'i == 47'.
- if (SecondTrueElement == Undefined)
- return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx);
-
- // True for two elements -> 'i == 47 | i == 72'.
- Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx);
- Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement);
- Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx);
- return BinaryOperator::CreateOr(C1, C2);
- }
-
- // If the comparison is only false for one or two elements, emit direct
- // comparisons.
- if (SecondFalseElement != Overdefined) {
- // None false -> true.
- if (FirstFalseElement == Undefined)
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
-
- Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement);
-
- // False for one element -> 'i != 47'.
- if (SecondFalseElement == Undefined)
- return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx);
-
- // False for two elements -> 'i != 47 & i != 72'.
- Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx);
- Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement);
- Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx);
- return BinaryOperator::CreateAnd(C1, C2);
- }
-
- // If the comparison can be replaced with a range comparison for the elements
- // where it is true, emit the range check.
- if (TrueRangeEnd != Overdefined) {
- assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare");
-
- // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1).
- if (FirstTrueElement) {
- Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement);
- Idx = Builder->CreateAdd(Idx, Offs);
- }
-
- Value *End = ConstantInt::get(Idx->getType(),
- TrueRangeEnd-FirstTrueElement+1);
- return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End);
- }
-
- // False range check.
- if (FalseRangeEnd != Overdefined) {
- assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare");
- // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse).
- if (FirstFalseElement) {
- Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement);
- Idx = Builder->CreateAdd(Idx, Offs);
- }
-
- Value *End = ConstantInt::get(Idx->getType(),
- FalseRangeEnd-FirstFalseElement);
- return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End);
- }
-
-
- // If a 32-bit or 64-bit magic bitvector captures the entire comparison state
- // of this load, replace it with computation that does:
- // ((magic_cst >> i) & 1) != 0
- if (Init->getNumOperands() <= 32 ||
- (TD && Init->getNumOperands() <= 64 && TD->isLegalInteger(64))) {
- const Type *Ty;
- if (Init->getNumOperands() <= 32)
- Ty = Type::getInt32Ty(Init->getContext());
- else
- Ty = Type::getInt64Ty(Init->getContext());
- Value *V = Builder->CreateIntCast(Idx, Ty, false);
- V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V);
- V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V);
- return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0));
- }
-
- return 0;
-}
-
-
-Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
- bool Changed = false;
-
- /// Orders the operands of the compare so that they are listed from most
- /// complex to least complex. This puts constants before unary operators,
- /// before binary operators.
- if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
- I.swapOperands();
- Changed = true;
- }
-
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (Value *V = SimplifyFCmpInst(I.getPredicate(), Op0, Op1, TD))
- return ReplaceInstUsesWith(I, V);
-
- // Simplify 'fcmp pred X, X'
- if (Op0 == Op1) {
- switch (I.getPredicate()) {
- default: llvm_unreachable("Unknown predicate!");
- case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
- case FCmpInst::FCMP_ULT: // True if unordered or less than
- case FCmpInst::FCMP_UGT: // True if unordered or greater than
- case FCmpInst::FCMP_UNE: // True if unordered or not equal
- // Canonicalize these to be 'fcmp uno %X, 0.0'.
- I.setPredicate(FCmpInst::FCMP_UNO);
- I.setOperand(1, Constant::getNullValue(Op0->getType()));
- return &I;
-
- case FCmpInst::FCMP_ORD: // True if ordered (no nans)
- case FCmpInst::FCMP_OEQ: // True if ordered and equal
- case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
- case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
- // Canonicalize these to be 'fcmp ord %X, 0.0'.
- I.setPredicate(FCmpInst::FCMP_ORD);
- I.setOperand(1, Constant::getNullValue(Op0->getType()));
- return &I;
- }
- }
-
- // Handle fcmp with constant RHS
- if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
- if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
- switch (LHSI->getOpcode()) {
- case Instruction::PHI:
- // Only fold fcmp into the PHI if the phi and fcmp are in the same
- // block. If in the same block, we're encouraging jump threading. If
- // not, we are just pessimizing the code by making an i1 phi.
- if (LHSI->getParent() == I.getParent())
- if (Instruction *NV = FoldOpIntoPhi(I, true))
- return NV;
- break;
- case Instruction::SIToFP:
- case Instruction::UIToFP:
- if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC))
- return NV;
- break;
- case Instruction::Select: {
- // If either operand of the select is a constant, we can fold the
- // comparison into the select arms, which will cause one to be
- // constant folded and the select turned into a bitwise or.
- Value *Op1 = 0, *Op2 = 0;
- if (LHSI->hasOneUse()) {
- if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
- // Fold the known value into the constant operand.
- Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
- // Insert a new FCmp of the other select operand.
- Op2 = Builder->CreateFCmp(I.getPredicate(),
- LHSI->getOperand(2), RHSC, I.getName());
- } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
- // Fold the known value into the constant operand.
- Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
- // Insert a new FCmp of the other select operand.
- Op1 = Builder->CreateFCmp(I.getPredicate(), LHSI->getOperand(1),
- RHSC, I.getName());
- }
- }
-
- if (Op1)
- return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
- break;
- }
- case Instruction::Load:
- if (GetElementPtrInst *GEP =
- dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
- if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
- !cast<LoadInst>(LHSI)->isVolatile())
- if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
- return Res;
- }
- break;
- }
- }
-
- return Changed ? &I : 0;
-}
-
-Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
- bool Changed = false;
-
- /// Orders the operands of the compare so that they are listed from most
- /// complex to least complex. This puts constants before unary operators,
- /// before binary operators.
- if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
- I.swapOperands();
- Changed = true;
- }
-
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, TD))
- return ReplaceInstUsesWith(I, V);
-
- const Type *Ty = Op0->getType();
-
- // icmp's with boolean values can always be turned into bitwise operations
- if (Ty == Type::getInt1Ty(*Context)) {
- switch (I.getPredicate()) {
- default: llvm_unreachable("Invalid icmp instruction!");
- case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B)
- Value *Xor = Builder->CreateXor(Op0, Op1, I.getName()+"tmp");
- return BinaryOperator::CreateNot(Xor);
- }
- case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B
- return BinaryOperator::CreateXor(Op0, Op1);
-
- case ICmpInst::ICMP_UGT:
- std::swap(Op0, Op1); // Change icmp ugt -> icmp ult
- // FALL THROUGH
- case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B
- Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
- return BinaryOperator::CreateAnd(Not, Op1);
- }
- case ICmpInst::ICMP_SGT:
- std::swap(Op0, Op1); // Change icmp sgt -> icmp slt
- // FALL THROUGH
- case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B
- Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
- return BinaryOperator::CreateAnd(Not, Op0);
- }
- case ICmpInst::ICMP_UGE:
- std::swap(Op0, Op1); // Change icmp uge -> icmp ule
- // FALL THROUGH
- case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B
- Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
- return BinaryOperator::CreateOr(Not, Op1);
- }
- case ICmpInst::ICMP_SGE:
- std::swap(Op0, Op1); // Change icmp sge -> icmp sle
- // FALL THROUGH
- case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B
- Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
- return BinaryOperator::CreateOr(Not, Op0);
- }
- }
- }
-
- unsigned BitWidth = 0;
- if (TD)
- BitWidth = TD->getTypeSizeInBits(Ty->getScalarType());
- else if (Ty->isIntOrIntVector())
- BitWidth = Ty->getScalarSizeInBits();
-
- bool isSignBit = false;
-
- // See if we are doing a comparison with a constant.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
- Value *A = 0, *B = 0;
-
- // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B)
- if (I.isEquality() && CI->isZero() &&
- match(Op0, m_Sub(m_Value(A), m_Value(B)))) {
- // (icmp cond A B) if cond is equality
- return new ICmpInst(I.getPredicate(), A, B);
- }
-
- // If we have an icmp le or icmp ge instruction, turn it into the
- // appropriate icmp lt or icmp gt instruction. This allows us to rely on
- // them being folded in the code below. The SimplifyICmpInst code has
- // already handled the edge cases for us, so we just assert on them.
- switch (I.getPredicate()) {
- default: break;
- case ICmpInst::ICMP_ULE:
- assert(!CI->isMaxValue(false)); // A <=u MAX -> TRUE
- return new ICmpInst(ICmpInst::ICMP_ULT, Op0,
- AddOne(CI));
- case ICmpInst::ICMP_SLE:
- assert(!CI->isMaxValue(true)); // A <=s MAX -> TRUE
- return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
- AddOne(CI));
- case ICmpInst::ICMP_UGE:
- assert(!CI->isMinValue(false)); // A >=u MIN -> TRUE
- return new ICmpInst(ICmpInst::ICMP_UGT, Op0,
- SubOne(CI));
- case ICmpInst::ICMP_SGE:
- assert(!CI->isMinValue(true)); // A >=s MIN -> TRUE
- return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
- SubOne(CI));
- }
-
- // If this comparison is a normal comparison, it demands all
- // bits, if it is a sign bit comparison, it only demands the sign bit.
- bool UnusedBit;
- isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
- }
-
- // See if we can fold the comparison based on range information we can get
- // by checking whether bits are known to be zero or one in the input.
- if (BitWidth != 0) {
- APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0);
- APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0);
-
- if (SimplifyDemandedBits(I.getOperandUse(0),
- isSignBit ? APInt::getSignBit(BitWidth)
- : APInt::getAllOnesValue(BitWidth),
- Op0KnownZero, Op0KnownOne, 0))
- return &I;
- if (SimplifyDemandedBits(I.getOperandUse(1),
- APInt::getAllOnesValue(BitWidth),
- Op1KnownZero, Op1KnownOne, 0))
- return &I;
-
- // Given the known and unknown bits, compute a range that the LHS could be
- // in. Compute the Min, Max and RHS values based on the known bits. For the
- // EQ and NE we use unsigned values.
- APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0);
- APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0);
- if (I.isSigned()) {
- ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
- Op0Min, Op0Max);
- ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
- Op1Min, Op1Max);
- } else {
- ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
- Op0Min, Op0Max);
- ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
- Op1Min, Op1Max);
- }
-
- // If Min and Max are known to be the same, then SimplifyDemandedBits
- // figured out that the LHS is a constant. Just constant fold this now so
- // that code below can assume that Min != Max.
- if (!isa<Constant>(Op0) && Op0Min == Op0Max)
- return new ICmpInst(I.getPredicate(),
- ConstantInt::get(*Context, Op0Min), Op1);
- if (!isa<Constant>(Op1) && Op1Min == Op1Max)
- return new ICmpInst(I.getPredicate(), Op0,
- ConstantInt::get(*Context, Op1Min));
-
- // Based on the range information we know about the LHS, see if we can
- // simplify this comparison. For example, (x&4) < 8 is always true.
- switch (I.getPredicate()) {
- default: llvm_unreachable("Unknown icmp opcode!");
- case ICmpInst::ICMP_EQ:
- if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- break;
- case ICmpInst::ICMP_NE:
- if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- break;
- case ICmpInst::ICMP_ULT:
- if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B)
- return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
- if (Op1Max == Op0Min+1) // A <u C -> A == C-1 if min(A)+1 == C
- return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
- SubOne(CI));
-
- // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
- if (CI->isMinValue(true))
- return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
- Constant::getAllOnesValue(Op0->getType()));
- }
- break;
- case ICmpInst::ICMP_UGT:
- if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
-
- if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B)
- return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
- if (Op1Min == Op0Max-1) // A >u C -> A == C+1 if max(a)-1 == C
- return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
- AddOne(CI));
-
- // (x >u 2147483647) -> (x <s 0) -> true if sign bit set
- if (CI->isMaxValue(true))
- return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
- Constant::getNullValue(Op0->getType()));
- }
- break;
- case ICmpInst::ICMP_SLT:
- if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B)
- return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
- if (Op1Max == Op0Min+1) // A <s C -> A == C-1 if min(A)+1 == C
- return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
- SubOne(CI));
- }
- break;
- case ICmpInst::ICMP_SGT:
- if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
-
- if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B)
- return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
- if (Op1Min == Op0Max-1) // A >s C -> A == C+1 if max(A)-1 == C
- return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
- AddOne(CI));
- }
- break;
- case ICmpInst::ICMP_SGE:
- assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!");
- if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- break;
- case ICmpInst::ICMP_SLE:
- assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!");
- if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- break;
- case ICmpInst::ICMP_UGE:
- assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!");
- if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- break;
- case ICmpInst::ICMP_ULE:
- assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!");
- if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
- if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
- break;
- }
-
- // Turn a signed comparison into an unsigned one if both operands
- // are known to have the same sign.
- if (I.isSigned() &&
- ((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) ||
- (Op0KnownOne.isNegative() && Op1KnownOne.isNegative())))
- return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
- }
-
- // Test if the ICmpInst instruction is used exclusively by a select as
- // part of a minimum or maximum operation. If so, refrain from doing
- // any other folding. This helps out other analyses which understand
- // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
- // and CodeGen. And in this case, at least one of the comparison
- // operands has at least one user besides the compare (the select),
- // which would often largely negate the benefit of folding anyway.
- if (I.hasOneUse())
- if (SelectInst *SI = dyn_cast<SelectInst>(*I.use_begin()))
- if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
- (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
- return 0;
-
- // See if we are doing a comparison between a constant and an instruction that
- // can be folded into the comparison.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
- // Since the RHS is a ConstantInt (CI), if the left hand side is an
- // instruction, see if that instruction also has constants so that the
- // instruction can be folded into the icmp
- if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
- if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
- return Res;
- }
-
- // Handle icmp with constant (but not simple integer constant) RHS
- if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
- if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
- switch (LHSI->getOpcode()) {
- case Instruction::GetElementPtr:
- // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
- if (RHSC->isNullValue() &&
- cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices())
- return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
- Constant::getNullValue(LHSI->getOperand(0)->getType()));
- break;
- case Instruction::PHI:
- // Only fold icmp into the PHI if the phi and icmp are in the same
- // block. If in the same block, we're encouraging jump threading. If
- // not, we are just pessimizing the code by making an i1 phi.
- if (LHSI->getParent() == I.getParent())
- if (Instruction *NV = FoldOpIntoPhi(I, true))
- return NV;
- break;
- case Instruction::Select: {
- // If either operand of the select is a constant, we can fold the
- // comparison into the select arms, which will cause one to be
- // constant folded and the select turned into a bitwise or.
- Value *Op1 = 0, *Op2 = 0;
- if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1)))
- Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
- if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2)))
- Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
-
- // We only want to perform this transformation if it will not lead to
- // additional code. This is true if either both sides of the select
- // fold to a constant (in which case the icmp is replaced with a select
- // which will usually simplify) or this is the only user of the
- // select (in which case we are trading a select+icmp for a simpler
- // select+icmp).
- if ((Op1 && Op2) || (LHSI->hasOneUse() && (Op1 || Op2))) {
- if (!Op1)
- Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1),
- RHSC, I.getName());
- if (!Op2)
- Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2),
- RHSC, I.getName());
- return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
- }
- break;
- }
- case Instruction::Call:
- // If we have (malloc != null), and if the malloc has a single use, we
- // can assume it is successful and remove the malloc.
- if (isMalloc(LHSI) && LHSI->hasOneUse() &&
- isa<ConstantPointerNull>(RHSC)) {
- // Need to explicitly erase malloc call here, instead of adding it to
- // Worklist, because it won't get DCE'd from the Worklist since
- // isInstructionTriviallyDead() returns false for function calls.
- // It is OK to replace LHSI/MallocCall with Undef because the
- // instruction that uses it will be erased via Worklist.
- if (extractMallocCall(LHSI)) {
- LHSI->replaceAllUsesWith(UndefValue::get(LHSI->getType()));
- EraseInstFromFunction(*LHSI);
- return ReplaceInstUsesWith(I,
- ConstantInt::get(Type::getInt1Ty(*Context),
- !I.isTrueWhenEqual()));
- }
- if (CallInst* MallocCall = extractMallocCallFromBitCast(LHSI))
- if (MallocCall->hasOneUse()) {
- MallocCall->replaceAllUsesWith(
- UndefValue::get(MallocCall->getType()));
- EraseInstFromFunction(*MallocCall);
- Worklist.Add(LHSI); // The malloc's bitcast use.
- return ReplaceInstUsesWith(I,
- ConstantInt::get(Type::getInt1Ty(*Context),
- !I.isTrueWhenEqual()));
- }
- }
- break;
- case Instruction::IntToPtr:
- // icmp pred inttoptr(X), null -> icmp pred X, 0
- if (RHSC->isNullValue() && TD &&
- TD->getIntPtrType(RHSC->getContext()) ==
- LHSI->getOperand(0)->getType())
- return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
- Constant::getNullValue(LHSI->getOperand(0)->getType()));
- break;
-
- case Instruction::Load:
- // Try to optimize things like "A[i] > 4" to index computations.
- if (GetElementPtrInst *GEP =
- dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
- if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
- !cast<LoadInst>(LHSI)->isVolatile())
- if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
- return Res;
- }
- break;
- }
- }
-
- // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
- if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0))
- if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
- return NI;
- if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1))
- if (Instruction *NI = FoldGEPICmp(GEP, Op0,
- ICmpInst::getSwappedPredicate(I.getPredicate()), I))
- return NI;
-
- // Test to see if the operands of the icmp are casted versions of other
- // values. If the ptr->ptr cast can be stripped off both arguments, we do so
- // now.
- if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
- if (isa<PointerType>(Op0->getType()) &&
- (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
- // We keep moving the cast from the left operand over to the right
- // operand, where it can often be eliminated completely.
- Op0 = CI->getOperand(0);
-
- // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
- // so eliminate it as well.
- if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
- Op1 = CI2->getOperand(0);
-
- // If Op1 is a constant, we can fold the cast into the constant.
- if (Op0->getType() != Op1->getType()) {
- if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
- Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
- } else {
- // Otherwise, cast the RHS right before the icmp
- Op1 = Builder->CreateBitCast(Op1, Op0->getType());
- }
- }
- return new ICmpInst(I.getPredicate(), Op0, Op1);
- }
- }
-
- if (isa<CastInst>(Op0)) {
- // Handle the special case of: icmp (cast bool to X), <cst>
- // This comes up when you have code like
- // int X = A < B;
- // if (X) ...
- // For generality, we handle any zero-extension of any operand comparison
- // with a constant or another cast from the same type.
- if (isa<Constant>(Op1) || isa<CastInst>(Op1))
- if (Instruction *R = visitICmpInstWithCastAndCast(I))
- return R;
- }
-
- // See if it's the same type of instruction on the left and right.
- if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
- if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
- if (Op0I->getOpcode() == Op1I->getOpcode() && Op0I->hasOneUse() &&
- Op1I->hasOneUse() && Op0I->getOperand(1) == Op1I->getOperand(1)) {
- switch (Op0I->getOpcode()) {
- default: break;
- case Instruction::Add:
- case Instruction::Sub:
- case Instruction::Xor:
- if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
- return new ICmpInst(I.getPredicate(), Op0I->getOperand(0),
- Op1I->getOperand(0));
- // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
- if (CI->getValue().isSignBit()) {
- ICmpInst::Predicate Pred = I.isSigned()
- ? I.getUnsignedPredicate()
- : I.getSignedPredicate();
- return new ICmpInst(Pred, Op0I->getOperand(0),
- Op1I->getOperand(0));
- }
-
- if (CI->getValue().isMaxSignedValue()) {
- ICmpInst::Predicate Pred = I.isSigned()
- ? I.getUnsignedPredicate()
- : I.getSignedPredicate();
- Pred = I.getSwappedPredicate(Pred);
- return new ICmpInst(Pred, Op0I->getOperand(0),
- Op1I->getOperand(0));
- }
- }
- break;
- case Instruction::Mul:
- if (!I.isEquality())
- break;
-
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
- // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask
- // Mask = -1 >> count-trailing-zeros(Cst).
- if (!CI->isZero() && !CI->isOne()) {
- const APInt &AP = CI->getValue();
- ConstantInt *Mask = ConstantInt::get(*Context,
- APInt::getLowBitsSet(AP.getBitWidth(),
- AP.getBitWidth() -
- AP.countTrailingZeros()));
- Value *And1 = Builder->CreateAnd(Op0I->getOperand(0), Mask);
- Value *And2 = Builder->CreateAnd(Op1I->getOperand(0), Mask);
- return new ICmpInst(I.getPredicate(), And1, And2);
- }
- }
- break;
- }
- }
- }
- }
-
- // ~x < ~y --> y < x
- { Value *A, *B;
- if (match(Op0, m_Not(m_Value(A))) &&
- match(Op1, m_Not(m_Value(B))))
- return new ICmpInst(I.getPredicate(), B, A);
- }
-
- if (I.isEquality()) {
- Value *A, *B, *C, *D;
-
- // -x == -y --> x == y
- if (match(Op0, m_Neg(m_Value(A))) &&
- match(Op1, m_Neg(m_Value(B))))
- return new ICmpInst(I.getPredicate(), A, B);
-
- if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
- if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
- Value *OtherVal = A == Op1 ? B : A;
- return new ICmpInst(I.getPredicate(), OtherVal,
- Constant::getNullValue(A->getType()));
- }
-
- if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
- // A^c1 == C^c2 --> A == C^(c1^c2)
- ConstantInt *C1, *C2;
- if (match(B, m_ConstantInt(C1)) &&
- match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) {
- Constant *NC =
- ConstantInt::get(*Context, C1->getValue() ^ C2->getValue());
- Value *Xor = Builder->CreateXor(C, NC, "tmp");
- return new ICmpInst(I.getPredicate(), A, Xor);
- }
-
- // A^B == A^D -> B == D
- if (A == C) return new ICmpInst(I.getPredicate(), B, D);
- if (A == D) return new ICmpInst(I.getPredicate(), B, C);
- if (B == C) return new ICmpInst(I.getPredicate(), A, D);
- if (B == D) return new ICmpInst(I.getPredicate(), A, C);
- }
- }
-
- if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
- (A == Op0 || B == Op0)) {
- // A == (A^B) -> B == 0
- Value *OtherVal = A == Op0 ? B : A;
- return new ICmpInst(I.getPredicate(), OtherVal,
- Constant::getNullValue(A->getType()));
- }
-
- // (A-B) == A -> B == 0
- if (match(Op0, m_Sub(m_Specific(Op1), m_Value(B))))
- return new ICmpInst(I.getPredicate(), B,
- Constant::getNullValue(B->getType()));
-
- // A == (A-B) -> B == 0
- if (match(Op1, m_Sub(m_Specific(Op0), m_Value(B))))
- return new ICmpInst(I.getPredicate(), B,
- Constant::getNullValue(B->getType()));
-
- // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
- if (Op0->hasOneUse() && Op1->hasOneUse() &&
- match(Op0, m_And(m_Value(A), m_Value(B))) &&
- match(Op1, m_And(m_Value(C), m_Value(D)))) {
- Value *X = 0, *Y = 0, *Z = 0;
-
- if (A == C) {
- X = B; Y = D; Z = A;
- } else if (A == D) {
- X = B; Y = C; Z = A;
- } else if (B == C) {
- X = A; Y = D; Z = B;
- } else if (B == D) {
- X = A; Y = C; Z = B;
- }
-
- if (X) { // Build (X^Y) & Z
- Op1 = Builder->CreateXor(X, Y, "tmp");
- Op1 = Builder->CreateAnd(Op1, Z, "tmp");
- I.setOperand(0, Op1);
- I.setOperand(1, Constant::getNullValue(Op1->getType()));
- return &I;
- }
- }
- }
-
- {
- Value *X; ConstantInt *Cst;
- // icmp X+Cst, X
- if (match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op1 == X)
- return FoldICmpAddOpCst(I, X, Cst, I.getPredicate(), Op0);
-
- // icmp X, X+Cst
- if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X)
- return FoldICmpAddOpCst(I, X, Cst, I.getSwappedPredicate(), Op1);
- }
- return Changed ? &I : 0;
-}
-
-/// FoldICmpAddOpCst - Fold "icmp pred (X+CI), X".
-Instruction *InstCombiner::FoldICmpAddOpCst(ICmpInst &ICI,
- Value *X, ConstantInt *CI,
- ICmpInst::Predicate Pred,
- Value *TheAdd) {
- // If we have X+0, exit early (simplifying logic below) and let it get folded
- // elsewhere. icmp X+0, X -> icmp X, X
- if (CI->isZero()) {
- bool isTrue = ICmpInst::isTrueWhenEqual(Pred);
- return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
- }
-
- // (X+4) == X -> false.
- if (Pred == ICmpInst::ICMP_EQ)
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext()));
-
- // (X+4) != X -> true.
- if (Pred == ICmpInst::ICMP_NE)
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext()));
-
- // If this is an instruction (as opposed to constantexpr) get NUW/NSW info.
- bool isNUW = false, isNSW = false;
- if (BinaryOperator *Add = dyn_cast<BinaryOperator>(TheAdd)) {
- isNUW = Add->hasNoUnsignedWrap();
- isNSW = Add->hasNoSignedWrap();
- }
-
- // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0,
- // so the values can never be equal. Similiarly for all other "or equals"
- // operators.
-
- // (X+1) <u X --> X >u (MAXUINT-1) --> X != 255
- // (X+2) <u X --> X >u (MAXUINT-2) --> X > 253
- // (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0
- if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) {
- // If this is an NUW add, then this is always false.
- if (isNUW)
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext()));
-
- Value *R = ConstantExpr::getSub(ConstantInt::get(CI->getType(), -1ULL), CI);
- return new ICmpInst(ICmpInst::ICMP_UGT, X, R);
- }
-
- // (X+1) >u X --> X <u (0-1) --> X != 255
- // (X+2) >u X --> X <u (0-2) --> X <u 254
- // (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0
- if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) {
- // If this is an NUW add, then this is always true.
- if (isNUW)
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext()));
- return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantExpr::getNeg(CI));
- }
-
- unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits();
- ConstantInt *SMax = ConstantInt::get(X->getContext(),
- APInt::getSignedMaxValue(BitWidth));
-
- // (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127
- // (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125
- // (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0
- // (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1
- // (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126
- // (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127
- if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) {
- // If this is an NSW add, then we have two cases: if the constant is
- // positive, then this is always false, if negative, this is always true.
- if (isNSW) {
- bool isTrue = CI->getValue().isNegative();
- return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
- }
-
- return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI));
- }
-
- // (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127
- // (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126
- // (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1
- // (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2
- // (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126
- // (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128
-
- // If this is an NSW add, then we have two cases: if the constant is
- // positive, then this is always true, if negative, this is always false.
- if (isNSW) {
- bool isTrue = !CI->getValue().isNegative();
- return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
- }
-
- assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE);
- Constant *C = ConstantInt::get(X->getContext(), CI->getValue()-1);
- return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C));
-}
-
-/// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
-/// and CmpRHS are both known to be integer constants.
-Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
- ConstantInt *DivRHS) {
- ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
- const APInt &CmpRHSV = CmpRHS->getValue();
-
- // FIXME: If the operand types don't match the type of the divide
- // then don't attempt this transform. The code below doesn't have the
- // logic to deal with a signed divide and an unsigned compare (and
- // vice versa). This is because (x /s C1) <s C2 produces different
- // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
- // (x /u C1) <u C2. Simply casting the operands and result won't
- // work. :( The if statement below tests that condition and bails
- // if it finds it.
- bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
- if (!ICI.isEquality() && DivIsSigned != ICI.isSigned())
- return 0;
- if (DivRHS->isZero())
- return 0; // The ProdOV computation fails on divide by zero.
- if (DivIsSigned && DivRHS->isAllOnesValue())
- return 0; // The overflow computation also screws up here
- if (DivRHS->isOne())
- return 0; // Not worth bothering, and eliminates some funny cases
- // with INT_MIN.
-
- // Compute Prod = CI * DivRHS. We are essentially solving an equation
- // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
- // C2 (CI). By solving for X we can turn this into a range check
- // instead of computing a divide.
- Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS);
-
- // Determine if the product overflows by seeing if the product is
- // not equal to the divide. Make sure we do the same kind of divide
- // as in the LHS instruction that we're folding.
- bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
- ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
-
- // Get the ICmp opcode
- ICmpInst::Predicate Pred = ICI.getPredicate();
-
- // Figure out the interval that is being checked. For example, a comparison
- // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
- // Compute this interval based on the constants involved and the signedness of
- // the compare/divide. This computes a half-open interval, keeping track of
- // whether either value in the interval overflows. After analysis each
- // overflow variable is set to 0 if it's corresponding bound variable is valid
- // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
- int LoOverflow = 0, HiOverflow = 0;
- Constant *LoBound = 0, *HiBound = 0;
-
- if (!DivIsSigned) { // udiv
- // e.g. X/5 op 3 --> [15, 20)
- LoBound = Prod;
- HiOverflow = LoOverflow = ProdOV;
- if (!HiOverflow)
- HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, Context, false);
- } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0.
- if (CmpRHSV == 0) { // (X / pos) op 0
- // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
- LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
- HiBound = DivRHS;
- } else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos
- LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
- HiOverflow = LoOverflow = ProdOV;
- if (!HiOverflow)
- HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, Context, true);
- } else { // (X / pos) op neg
- // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
- HiBound = AddOne(Prod);
- LoOverflow = HiOverflow = ProdOV ? -1 : 0;
- if (!LoOverflow) {
- ConstantInt* DivNeg =
- cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
- LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, Context,
- true) ? -1 : 0;
- }
- }
- } else if (DivRHS->getValue().isNegative()) { // Divisor is < 0.
- if (CmpRHSV == 0) { // (X / neg) op 0
- // e.g. X/-5 op 0 --> [-4, 5)
- LoBound = AddOne(DivRHS);
- HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
- if (HiBound == DivRHS) { // -INTMIN = INTMIN
- HiOverflow = 1; // [INTMIN+1, overflow)
- HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN
- }
- } else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos
- // e.g. X/-5 op 3 --> [-19, -14)
- HiBound = AddOne(Prod);
- HiOverflow = LoOverflow = ProdOV ? -1 : 0;
- if (!LoOverflow)
- LoOverflow = AddWithOverflow(LoBound, HiBound,
- DivRHS, Context, true) ? -1 : 0;
- } else { // (X / neg) op neg
- LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20)
- LoOverflow = HiOverflow = ProdOV;
- if (!HiOverflow)
- HiOverflow = SubWithOverflow(HiBound, Prod, DivRHS, Context, true);
- }
-
- // Dividing by a negative swaps the condition. LT <-> GT
- Pred = ICmpInst::getSwappedPredicate(Pred);
- }
-
- Value *X = DivI->getOperand(0);
- switch (Pred) {
- default: llvm_unreachable("Unhandled icmp opcode!");
- case ICmpInst::ICMP_EQ:
- if (LoOverflow && HiOverflow)
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
- else if (HiOverflow)
- return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
- ICmpInst::ICMP_UGE, X, LoBound);
- else if (LoOverflow)
- return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
- ICmpInst::ICMP_ULT, X, HiBound);
- else
- return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI);
- case ICmpInst::ICMP_NE:
- if (LoOverflow && HiOverflow)
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
- else if (HiOverflow)
- return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
- ICmpInst::ICMP_ULT, X, LoBound);
- else if (LoOverflow)
- return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
- ICmpInst::ICMP_UGE, X, HiBound);
- else
- return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI);
- case ICmpInst::ICMP_ULT:
- case ICmpInst::ICMP_SLT:
- if (LoOverflow == +1) // Low bound is greater than input range.
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
- if (LoOverflow == -1) // Low bound is less than input range.
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
- return new ICmpInst(Pred, X, LoBound);
- case ICmpInst::ICMP_UGT:
- case ICmpInst::ICMP_SGT:
- if (HiOverflow == +1) // High bound greater than input range.
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
- else if (HiOverflow == -1) // High bound less than input range.
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
- if (Pred == ICmpInst::ICMP_UGT)
- return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
- else
- return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
- }
-}
-
-
-/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
-///
-Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
- Instruction *LHSI,
- ConstantInt *RHS) {
- const APInt &RHSV = RHS->getValue();
-
- switch (LHSI->getOpcode()) {
- case Instruction::Trunc:
- if (ICI.isEquality() && LHSI->hasOneUse()) {
- // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
- // of the high bits truncated out of x are known.
- unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(),
- SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits();
- APInt Mask(APInt::getHighBitsSet(SrcBits, SrcBits-DstBits));
- APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0);
- ComputeMaskedBits(LHSI->getOperand(0), Mask, KnownZero, KnownOne);
-
- // If all the high bits are known, we can do this xform.
- if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) {
- // Pull in the high bits from known-ones set.
- APInt NewRHS(RHS->getValue());
- NewRHS.zext(SrcBits);
- NewRHS |= KnownOne;
- return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
- ConstantInt::get(*Context, NewRHS));
- }
- }
- break;
-
- case Instruction::Xor: // (icmp pred (xor X, XorCST), CI)
- if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
- // If this is a comparison that tests the signbit (X < 0) or (x > -1),
- // fold the xor.
- if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) ||
- (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) {
- Value *CompareVal = LHSI->getOperand(0);
-
- // If the sign bit of the XorCST is not set, there is no change to
- // the operation, just stop using the Xor.
- if (!XorCST->getValue().isNegative()) {
- ICI.setOperand(0, CompareVal);
- Worklist.Add(LHSI);
- return &ICI;
- }
-
- // Was the old condition true if the operand is positive?
- bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
-
- // If so, the new one isn't.
- isTrueIfPositive ^= true;
-
- if (isTrueIfPositive)
- return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal,
- SubOne(RHS));
- else
- return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal,
- AddOne(RHS));
- }
-
- if (LHSI->hasOneUse()) {
- // (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit))
- if (!ICI.isEquality() && XorCST->getValue().isSignBit()) {
- const APInt &SignBit = XorCST->getValue();
- ICmpInst::Predicate Pred = ICI.isSigned()
- ? ICI.getUnsignedPredicate()
- : ICI.getSignedPredicate();
- return new ICmpInst(Pred, LHSI->getOperand(0),
- ConstantInt::get(*Context, RHSV ^ SignBit));
- }
-
- // (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A)
- if (!ICI.isEquality() && XorCST->getValue().isMaxSignedValue()) {
- const APInt &NotSignBit = XorCST->getValue();
- ICmpInst::Predicate Pred = ICI.isSigned()
- ? ICI.getUnsignedPredicate()
- : ICI.getSignedPredicate();
- Pred = ICI.getSwappedPredicate(Pred);
- return new ICmpInst(Pred, LHSI->getOperand(0),
- ConstantInt::get(*Context, RHSV ^ NotSignBit));
- }
- }
- }
- break;
- case Instruction::And: // (icmp pred (and X, AndCST), RHS)
- if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
- LHSI->getOperand(0)->hasOneUse()) {
- ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
-
- // If the LHS is an AND of a truncating cast, we can widen the
- // and/compare to be the input width without changing the value
- // produced, eliminating a cast.
- if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
- // We can do this transformation if either the AND constant does not
- // have its sign bit set or if it is an equality comparison.
- // Extending a relational comparison when we're checking the sign
- // bit would not work.
- if (Cast->hasOneUse() &&
- (ICI.isEquality() ||
- (AndCST->getValue().isNonNegative() && RHSV.isNonNegative()))) {
- uint32_t BitWidth =
- cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth();
- APInt NewCST = AndCST->getValue();
- NewCST.zext(BitWidth);
- APInt NewCI = RHSV;
- NewCI.zext(BitWidth);
- Value *NewAnd =
- Builder->CreateAnd(Cast->getOperand(0),
- ConstantInt::get(*Context, NewCST), LHSI->getName());
- return new ICmpInst(ICI.getPredicate(), NewAnd,
- ConstantInt::get(*Context, NewCI));
- }
- }
-
- // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
- // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
- // happens a LOT in code produced by the C front-end, for bitfield
- // access.
- BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
- if (Shift && !Shift->isShift())
- Shift = 0;
-
- ConstantInt *ShAmt;
- ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0;
- const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift.
- const Type *AndTy = AndCST->getType(); // Type of the and.
-
- // We can fold this as long as we can't shift unknown bits
- // into the mask. This can only happen with signed shift
- // rights, as they sign-extend.
- if (ShAmt) {
- bool CanFold = Shift->isLogicalShift();
- if (!CanFold) {
- // To test for the bad case of the signed shr, see if any
- // of the bits shifted in could be tested after the mask.
- uint32_t TyBits = Ty->getPrimitiveSizeInBits();
- int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits);
-
- uint32_t BitWidth = AndTy->getPrimitiveSizeInBits();
- if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) &
- AndCST->getValue()) == 0)
- CanFold = true;
- }
-
- if (CanFold) {
- Constant *NewCst;
- if (Shift->getOpcode() == Instruction::Shl)
- NewCst = ConstantExpr::getLShr(RHS, ShAmt);
- else
- NewCst = ConstantExpr::getShl(RHS, ShAmt);
-
- // Check to see if we are shifting out any of the bits being
- // compared.
- if (ConstantExpr::get(Shift->getOpcode(),
- NewCst, ShAmt) != RHS) {
- // If we shifted bits out, the fold is not going to work out.
- // As a special case, check to see if this means that the
- // result is always true or false now.
- if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
- if (ICI.getPredicate() == ICmpInst::ICMP_NE)
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
- } else {
- ICI.setOperand(1, NewCst);
- Constant *NewAndCST;
- if (Shift->getOpcode() == Instruction::Shl)
- NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt);
- else
- NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
- LHSI->setOperand(1, NewAndCST);
- LHSI->setOperand(0, Shift->getOperand(0));
- Worklist.Add(Shift); // Shift is dead.
- return &ICI;
- }
- }
- }
-
- // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
- // preferable because it allows the C<<Y expression to be hoisted out
- // of a loop if Y is invariant and X is not.
- if (Shift && Shift->hasOneUse() && RHSV == 0 &&
- ICI.isEquality() && !Shift->isArithmeticShift() &&
- !isa<Constant>(Shift->getOperand(0))) {
- // Compute C << Y.
- Value *NS;
- if (Shift->getOpcode() == Instruction::LShr) {
- NS = Builder->CreateShl(AndCST, Shift->getOperand(1), "tmp");
- } else {
- // Insert a logical shift.
- NS = Builder->CreateLShr(AndCST, Shift->getOperand(1), "tmp");
- }
-
- // Compute X & (C << Y).
- Value *NewAnd =
- Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName());
-
- ICI.setOperand(0, NewAnd);
- return &ICI;
- }
- }
-
- // Try to optimize things like "A[i]&42 == 0" to index computations.
- if (LoadInst *LI = dyn_cast<LoadInst>(LHSI->getOperand(0))) {
- if (GetElementPtrInst *GEP =
- dyn_cast<GetElementPtrInst>(LI->getOperand(0)))
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
- if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
- !LI->isVolatile() && isa<ConstantInt>(LHSI->getOperand(1))) {
- ConstantInt *C = cast<ConstantInt>(LHSI->getOperand(1));
- if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV,ICI, C))
- return Res;
- }
- }
- break;
-
- case Instruction::Or: {
- if (!ICI.isEquality() || !RHS->isNullValue() || !LHSI->hasOneUse())
- break;
- Value *P, *Q;
- if (match(LHSI, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) {
- // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0
- // -> and (icmp eq P, null), (icmp eq Q, null).
-
- Value *ICIP = Builder->CreateICmp(ICI.getPredicate(), P,
- Constant::getNullValue(P->getType()));
- Value *ICIQ = Builder->CreateICmp(ICI.getPredicate(), Q,
- Constant::getNullValue(Q->getType()));
- Instruction *Op;
- if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
- Op = BinaryOperator::CreateAnd(ICIP, ICIQ);
- else
- Op = BinaryOperator::CreateOr(ICIP, ICIQ);
- return Op;
- }
- break;
- }
-
- case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
- ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
- if (!ShAmt) break;
-
- uint32_t TypeBits = RHSV.getBitWidth();
-
- // Check that the shift amount is in range. If not, don't perform
- // undefined shifts. When the shift is visited it will be
- // simplified.
- if (ShAmt->uge(TypeBits))
- break;
-
- if (ICI.isEquality()) {
- // If we are comparing against bits always shifted out, the
- // comparison cannot succeed.
- Constant *Comp =
- ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt),
- ShAmt);
- if (Comp != RHS) {// Comparing against a bit that we know is zero.
- bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
- Constant *Cst = ConstantInt::get(Type::getInt1Ty(*Context), IsICMP_NE);
- return ReplaceInstUsesWith(ICI, Cst);
- }
-
- if (LHSI->hasOneUse()) {
- // Otherwise strength reduce the shift into an and.
- uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
- Constant *Mask =
- ConstantInt::get(*Context, APInt::getLowBitsSet(TypeBits,
- TypeBits-ShAmtVal));
-
- Value *And =
- Builder->CreateAnd(LHSI->getOperand(0),Mask, LHSI->getName()+".mask");
- return new ICmpInst(ICI.getPredicate(), And,
- ConstantInt::get(*Context, RHSV.lshr(ShAmtVal)));
- }
- }
-
- // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
- bool TrueIfSigned = false;
- if (LHSI->hasOneUse() &&
- isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
- // (X << 31) <s 0 --> (X&1) != 0
- Constant *Mask = ConstantInt::get(*Context, APInt(TypeBits, 1) <<
- (TypeBits-ShAmt->getZExtValue()-1));
- Value *And =
- Builder->CreateAnd(LHSI->getOperand(0), Mask, LHSI->getName()+".mask");
- return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
- And, Constant::getNullValue(And->getType()));
- }
- break;
- }
-
- case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
- case Instruction::AShr: {
- // Only handle equality comparisons of shift-by-constant.
- ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
- if (!ShAmt || !ICI.isEquality()) break;
-
- // Check that the shift amount is in range. If not, don't perform
- // undefined shifts. When the shift is visited it will be
- // simplified.
- uint32_t TypeBits = RHSV.getBitWidth();
- if (ShAmt->uge(TypeBits))
- break;
-
- uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
-
- // If we are comparing against bits always shifted out, the
- // comparison cannot succeed.
- APInt Comp = RHSV << ShAmtVal;
- if (LHSI->getOpcode() == Instruction::LShr)
- Comp = Comp.lshr(ShAmtVal);
- else
- Comp = Comp.ashr(ShAmtVal);
-
- if (Comp != RHSV) { // Comparing against a bit that we know is zero.
- bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
- Constant *Cst = ConstantInt::get(Type::getInt1Ty(*Context), IsICMP_NE);
- return ReplaceInstUsesWith(ICI, Cst);
- }
-
- // Otherwise, check to see if the bits shifted out are known to be zero.
- // If so, we can compare against the unshifted value:
- // (X & 4) >> 1 == 2 --> (X & 4) == 4.
- if (LHSI->hasOneUse() &&
- MaskedValueIsZero(LHSI->getOperand(0),
- APInt::getLowBitsSet(Comp.getBitWidth(), ShAmtVal))) {
- return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
- ConstantExpr::getShl(RHS, ShAmt));
- }
-
- if (LHSI->hasOneUse()) {
- // Otherwise strength reduce the shift into an and.
- APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
- Constant *Mask = ConstantInt::get(*Context, Val);
-
- Value *And = Builder->CreateAnd(LHSI->getOperand(0),
- Mask, LHSI->getName()+".mask");
- return new ICmpInst(ICI.getPredicate(), And,
- ConstantExpr::getShl(RHS, ShAmt));
- }
- break;
- }
-
- case Instruction::SDiv:
- case Instruction::UDiv:
- // Fold: icmp pred ([us]div X, C1), C2 -> range test
- // Fold this div into the comparison, producing a range check.
- // Determine, based on the divide type, what the range is being
- // checked. If there is an overflow on the low or high side, remember
- // it, otherwise compute the range [low, hi) bounding the new value.
- // See: InsertRangeTest above for the kinds of replacements possible.
- if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
- if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
- DivRHS))
- return R;
- break;
-
- case Instruction::Add:
- // Fold: icmp pred (add X, C1), C2
- if (!ICI.isEquality()) {
- ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1));
- if (!LHSC) break;
- const APInt &LHSV = LHSC->getValue();
-
- ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV)
- .subtract(LHSV);
-
- if (ICI.isSigned()) {
- if (CR.getLower().isSignBit()) {
- return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0),
- ConstantInt::get(*Context, CR.getUpper()));
- } else if (CR.getUpper().isSignBit()) {
- return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0),
- ConstantInt::get(*Context, CR.getLower()));
- }
- } else {
- if (CR.getLower().isMinValue()) {
- return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0),
- ConstantInt::get(*Context, CR.getUpper()));
- } else if (CR.getUpper().isMinValue()) {
- return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0),
- ConstantInt::get(*Context, CR.getLower()));
- }
- }
- }
- break;
- }
-
- // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
- if (ICI.isEquality()) {
- bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
-
- // If the first operand is (add|sub|and|or|xor|rem) with a constant, and
- // the second operand is a constant, simplify a bit.
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
- switch (BO->getOpcode()) {
- case Instruction::SRem:
- // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
- if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
- const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
- if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) {
- Value *NewRem =
- Builder->CreateURem(BO->getOperand(0), BO->getOperand(1),
- BO->getName());
- return new ICmpInst(ICI.getPredicate(), NewRem,
- Constant::getNullValue(BO->getType()));
- }
- }
- break;
- case Instruction::Add:
- // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
- if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
- if (BO->hasOneUse())
- return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
- ConstantExpr::getSub(RHS, BOp1C));
- } else if (RHSV == 0) {
- // Replace ((add A, B) != 0) with (A != -B) if A or B is
- // efficiently invertible, or if the add has just this one use.
- Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
-
- if (Value *NegVal = dyn_castNegVal(BOp1))
- return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
- else if (Value *NegVal = dyn_castNegVal(BOp0))
- return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
- else if (BO->hasOneUse()) {
- Value *Neg = Builder->CreateNeg(BOp1);
- Neg->takeName(BO);
- return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
- }
- }
- break;
- case Instruction::Xor:
- // For the xor case, we can xor two constants together, eliminating
- // the explicit xor.
- if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
- return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
- ConstantExpr::getXor(RHS, BOC));
-
- // FALLTHROUGH
- case Instruction::Sub:
- // Replace (([sub|xor] A, B) != 0) with (A != B)
- if (RHSV == 0)
- return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
- BO->getOperand(1));
- break;
-
- case Instruction::Or:
- // If bits are being or'd in that are not present in the constant we
- // are comparing against, then the comparison could never succeed!
- if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
- Constant *NotCI = ConstantExpr::getNot(RHS);
- if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
- return ReplaceInstUsesWith(ICI,
- ConstantInt::get(Type::getInt1Ty(*Context),
- isICMP_NE));
- }
- break;
-
- case Instruction::And:
- if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
- // If bits are being compared against that are and'd out, then the
- // comparison can never succeed!
- if ((RHSV & ~BOC->getValue()) != 0)
- return ReplaceInstUsesWith(ICI,
- ConstantInt::get(Type::getInt1Ty(*Context),
- isICMP_NE));
-
- // If we have ((X & C) == C), turn it into ((X & C) != 0).
- if (RHS == BOC && RHSV.isPowerOf2())
- return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
- ICmpInst::ICMP_NE, LHSI,
- Constant::getNullValue(RHS->getType()));
-
- // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
- if (BOC->getValue().isSignBit()) {
- Value *X = BO->getOperand(0);
- Constant *Zero = Constant::getNullValue(X->getType());
- ICmpInst::Predicate pred = isICMP_NE ?
- ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
- return new ICmpInst(pred, X, Zero);
- }
-
- // ((X & ~7) == 0) --> X < 8
- if (RHSV == 0 && isHighOnes(BOC)) {
- Value *X = BO->getOperand(0);
- Constant *NegX = ConstantExpr::getNeg(BOC);
- ICmpInst::Predicate pred = isICMP_NE ?
- ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
- return new ICmpInst(pred, X, NegX);
- }
- }
- default: break;
- }
- } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
- // Handle icmp {eq|ne} <intrinsic>, intcst.
- if (II->getIntrinsicID() == Intrinsic::bswap) {
- Worklist.Add(II);
- ICI.setOperand(0, II->getOperand(1));
- ICI.setOperand(1, ConstantInt::get(*Context, RHSV.byteSwap()));
- return &ICI;
- }
- }
- }
- return 0;
-}
-
-/// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
-/// We only handle extending casts so far.
-///
-Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
- const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
- Value *LHSCIOp = LHSCI->getOperand(0);
- const Type *SrcTy = LHSCIOp->getType();
- const Type *DestTy = LHSCI->getType();
- Value *RHSCIOp;
-
- // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
- // integer type is the same size as the pointer type.
- if (TD && LHSCI->getOpcode() == Instruction::PtrToInt &&
- TD->getPointerSizeInBits() ==
- cast<IntegerType>(DestTy)->getBitWidth()) {
- Value *RHSOp = 0;
- if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
- RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
- } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
- RHSOp = RHSC->getOperand(0);
- // If the pointer types don't match, insert a bitcast.
- if (LHSCIOp->getType() != RHSOp->getType())
- RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType());
- }
-
- if (RHSOp)
- return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
- }
-
- // The code below only handles extension cast instructions, so far.
- // Enforce this.
- if (LHSCI->getOpcode() != Instruction::ZExt &&
- LHSCI->getOpcode() != Instruction::SExt)
- return 0;
-
- bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
- bool isSignedCmp = ICI.isSigned();
-
- if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
- // Not an extension from the same type?
- RHSCIOp = CI->getOperand(0);
- if (RHSCIOp->getType() != LHSCIOp->getType())
- return 0;
-
- // If the signedness of the two casts doesn't agree (i.e. one is a sext
- // and the other is a zext), then we can't handle this.
- if (CI->getOpcode() != LHSCI->getOpcode())
- return 0;
-
- // Deal with equality cases early.
- if (ICI.isEquality())
- return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
-
- // A signed comparison of sign extended values simplifies into a
- // signed comparison.
- if (isSignedCmp && isSignedExt)
- return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
-
- // The other three cases all fold into an unsigned comparison.
- return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
- }
-
- // If we aren't dealing with a constant on the RHS, exit early
- ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
- if (!CI)
- return 0;
-
- // Compute the constant that would happen if we truncated to SrcTy then
- // reextended to DestTy.
- Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
- Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(),
- Res1, DestTy);
-
- // If the re-extended constant didn't change...
- if (Res2 == CI) {
- // Deal with equality cases early.
- if (ICI.isEquality())
- return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
-
- // A signed comparison of sign extended values simplifies into a
- // signed comparison.
- if (isSignedExt && isSignedCmp)
- return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
-
- // The other three cases all fold into an unsigned comparison.
- return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, Res1);
- }
-
- // The re-extended constant changed so the constant cannot be represented
- // in the shorter type. Consequently, we cannot emit a simple comparison.
-
- // First, handle some easy cases. We know the result cannot be equal at this
- // point so handle the ICI.isEquality() cases
- if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
- if (ICI.getPredicate() == ICmpInst::ICMP_NE)
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
-
- // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
- // should have been folded away previously and not enter in here.
- Value *Result;
- if (isSignedCmp) {
- // We're performing a signed comparison.
- if (cast<ConstantInt>(CI)->getValue().isNegative())
- Result = ConstantInt::getFalse(*Context); // X < (small) --> false
- else
- Result = ConstantInt::getTrue(*Context); // X < (large) --> true
- } else {
- // We're performing an unsigned comparison.
- if (isSignedExt) {
- // We're performing an unsigned comp with a sign extended value.
- // This is true if the input is >= 0. [aka >s -1]
- Constant *NegOne = Constant::getAllOnesValue(SrcTy);
- Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICI.getName());
- } else {
- // Unsigned extend & unsigned compare -> always true.
- Result = ConstantInt::getTrue(*Context);
- }
- }
-
- // Finally, return the value computed.
- if (ICI.getPredicate() == ICmpInst::ICMP_ULT ||
- ICI.getPredicate() == ICmpInst::ICMP_SLT)
- return ReplaceInstUsesWith(ICI, Result);
-
- assert((ICI.getPredicate()==ICmpInst::ICMP_UGT ||
- ICI.getPredicate()==ICmpInst::ICMP_SGT) &&
- "ICmp should be folded!");
- if (Constant *CI = dyn_cast<Constant>(Result))
- return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI));
- return BinaryOperator::CreateNot(Result);
-}
-
-Instruction *InstCombiner::visitShl(BinaryOperator &I) {
- return commonShiftTransforms(I);
-}
-
-Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
- return commonShiftTransforms(I);
-}
-
-Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
- if (Instruction *R = commonShiftTransforms(I))
- return R;
-
- Value *Op0 = I.getOperand(0);
-
- // ashr int -1, X = -1 (for any arithmetic shift rights of ~0)
- if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
- if (CSI->isAllOnesValue())
- return ReplaceInstUsesWith(I, CSI);
-
- // See if we can turn a signed shr into an unsigned shr.
- if (MaskedValueIsZero(Op0,
- APInt::getSignBit(I.getType()->getScalarSizeInBits())))
- return BinaryOperator::CreateLShr(Op0, I.getOperand(1));
-
- // Arithmetic shifting an all-sign-bit value is a no-op.
- unsigned NumSignBits = ComputeNumSignBits(Op0);
- if (NumSignBits == Op0->getType()->getScalarSizeInBits())
- return ReplaceInstUsesWith(I, Op0);
-
- return 0;
-}
-
-Instruction *InstCombiner::commonShiftTransforms(BinaryOperator &I) {
- assert(I.getOperand(1)->getType() == I.getOperand(0)->getType());
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- // shl X, 0 == X and shr X, 0 == X
- // shl 0, X == 0 and shr 0, X == 0
- if (Op1 == Constant::getNullValue(Op1->getType()) ||
- Op0 == Constant::getNullValue(Op0->getType()))
- return ReplaceInstUsesWith(I, Op0);
-
- if (isa<UndefValue>(Op0)) {
- if (I.getOpcode() == Instruction::AShr) // undef >>s X -> undef
- return ReplaceInstUsesWith(I, Op0);
- else // undef << X -> 0, undef >>u X -> 0
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
- }
- if (isa<UndefValue>(Op1)) {
- if (I.getOpcode() == Instruction::AShr) // X >>s undef -> X
- return ReplaceInstUsesWith(I, Op0);
- else // X << undef, X >>u undef -> 0
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
- }
-
- // See if we can fold away this shift.
- if (SimplifyDemandedInstructionBits(I))
- return &I;
-
- // Try to fold constant and into select arguments.
- if (isa<Constant>(Op0))
- if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
- if (Instruction *R = FoldOpIntoSelect(I, SI, this))
- return R;
-
- if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op1))
- if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
- return Res;
- return 0;
-}
-
-Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
- BinaryOperator &I) {
- bool isLeftShift = I.getOpcode() == Instruction::Shl;
-
- // See if we can simplify any instructions used by the instruction whose sole
- // purpose is to compute bits we don't care about.
- uint32_t TypeBits = Op0->getType()->getScalarSizeInBits();
-
- // shl i32 X, 32 = 0 and srl i8 Y, 9 = 0, ... just don't eliminate
- // a signed shift.
- //
- if (Op1->uge(TypeBits)) {
- if (I.getOpcode() != Instruction::AShr)
- return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
- else {
- I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
- return &I;
- }
- }
-
- // ((X*C1) << C2) == (X * (C1 << C2))
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
- if (BO->getOpcode() == Instruction::Mul && isLeftShift)
- if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
- return BinaryOperator::CreateMul(BO->getOperand(0),
- ConstantExpr::getShl(BOOp, Op1));
-
- // Try to fold constant and into select arguments.
- if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
- if (Instruction *R = FoldOpIntoSelect(I, SI, this))
- return R;
- if (isa<PHINode>(Op0))
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
-
- // Fold shift2(trunc(shift1(x,c1)), c2) -> trunc(shift2(shift1(x,c1),c2))
- if (TruncInst *TI = dyn_cast<TruncInst>(Op0)) {
- Instruction *TrOp = dyn_cast<Instruction>(TI->getOperand(0));
- // If 'shift2' is an ashr, we would have to get the sign bit into a funny
- // place. Don't try to do this transformation in this case. Also, we
- // require that the input operand is a shift-by-constant so that we have
- // confidence that the shifts will get folded together. We could do this
- // xform in more cases, but it is unlikely to be profitable.
- if (TrOp && I.isLogicalShift() && TrOp->isShift() &&
- isa<ConstantInt>(TrOp->getOperand(1))) {
- // Okay, we'll do this xform. Make the shift of shift.
- Constant *ShAmt = ConstantExpr::getZExt(Op1, TrOp->getType());
- // (shift2 (shift1 & 0x00FF), c2)
- Value *NSh = Builder->CreateBinOp(I.getOpcode(), TrOp, ShAmt,I.getName());
-
- // For logical shifts, the truncation has the effect of making the high
- // part of the register be zeros. Emulate this by inserting an AND to
- // clear the top bits as needed. This 'and' will usually be zapped by
- // other xforms later if dead.
- unsigned SrcSize = TrOp->getType()->getScalarSizeInBits();
- unsigned DstSize = TI->getType()->getScalarSizeInBits();
- APInt MaskV(APInt::getLowBitsSet(SrcSize, DstSize));
-
- // The mask we constructed says what the trunc would do if occurring
- // between the shifts. We want to know the effect *after* the second
- // shift. We know that it is a logical shift by a constant, so adjust the
- // mask as appropriate.
- if (I.getOpcode() == Instruction::Shl)
- MaskV <<= Op1->getZExtValue();
- else {
- assert(I.getOpcode() == Instruction::LShr && "Unknown logical shift");
- MaskV = MaskV.lshr(Op1->getZExtValue());
- }
-
- // shift1 & 0x00FF
- Value *And = Builder->CreateAnd(NSh, ConstantInt::get(*Context, MaskV),
- TI->getName());
-
- // Return the value truncated to the interesting size.
- return new TruncInst(And, I.getType());
- }
- }
-
- if (Op0->hasOneUse()) {
- if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
- // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
- Value *V1, *V2;
- ConstantInt *CC;
- switch (Op0BO->getOpcode()) {
- default: break;
- case Instruction::Add:
- case Instruction::And:
- case Instruction::Or:
- case Instruction::Xor: {
- // These operators commute.
- // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
- if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
- match(Op0BO->getOperand(1), m_Shr(m_Value(V1),
- m_Specific(Op1)))) {
- Value *YS = // (Y << C)
- Builder->CreateShl(Op0BO->getOperand(0), Op1, Op0BO->getName());
- // (X + (Y << C))
- Value *X = Builder->CreateBinOp(Op0BO->getOpcode(), YS, V1,
- Op0BO->getOperand(1)->getName());
- uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
- return BinaryOperator::CreateAnd(X, ConstantInt::get(*Context,
- APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
- }
-
- // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
- Value *Op0BOOp1 = Op0BO->getOperand(1);
- if (isLeftShift && Op0BOOp1->hasOneUse() &&
- match(Op0BOOp1,
- m_And(m_Shr(m_Value(V1), m_Specific(Op1)),
- m_ConstantInt(CC))) &&
- cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse()) {
- Value *YS = // (Y << C)
- Builder->CreateShl(Op0BO->getOperand(0), Op1,
- Op0BO->getName());
- // X & (CC << C)
- Value *XM = Builder->CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
- V1->getName()+".mask");
- return BinaryOperator::Create(Op0BO->getOpcode(), YS, XM);
- }
- }
-
- // FALL THROUGH.
- case Instruction::Sub: {
- // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
- if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
- match(Op0BO->getOperand(0), m_Shr(m_Value(V1),
- m_Specific(Op1)))) {
- Value *YS = // (Y << C)
- Builder->CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
- // (X + (Y << C))
- Value *X = Builder->CreateBinOp(Op0BO->getOpcode(), V1, YS,
- Op0BO->getOperand(0)->getName());
- uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
- return BinaryOperator::CreateAnd(X, ConstantInt::get(*Context,
- APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
- }
-
- // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
- if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
- match(Op0BO->getOperand(0),
- m_And(m_Shr(m_Value(V1), m_Value(V2)),
- m_ConstantInt(CC))) && V2 == Op1 &&
- cast<BinaryOperator>(Op0BO->getOperand(0))
- ->getOperand(0)->hasOneUse()) {
- Value *YS = // (Y << C)
- Builder->CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
- // X & (CC << C)
- Value *XM = Builder->CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
- V1->getName()+".mask");
-
- return BinaryOperator::Create(Op0BO->getOpcode(), XM, YS);
- }
-
- break;
- }
- }
-
-
- // If the operand is an bitwise operator with a constant RHS, and the
- // shift is the only use, we can pull it out of the shift.
- if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
- bool isValid = true; // Valid only for And, Or, Xor
- bool highBitSet = false; // Transform if high bit of constant set?
-
- switch (Op0BO->getOpcode()) {
- default: isValid = false; break; // Do not perform transform!
- case Instruction::Add:
- isValid = isLeftShift;
- break;
- case Instruction::Or:
- case Instruction::Xor:
- highBitSet = false;
- break;
- case Instruction::And:
- highBitSet = true;
- break;
- }
-
- // If this is a signed shift right, and the high bit is modified
- // by the logical operation, do not perform the transformation.
- // The highBitSet boolean indicates the value of the high bit of
- // the constant which would cause it to be modified for this
- // operation.
- //
- if (isValid && I.getOpcode() == Instruction::AShr)
- isValid = Op0C->getValue()[TypeBits-1] == highBitSet;
-
- if (isValid) {
- Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
-
- Value *NewShift =
- Builder->CreateBinOp(I.getOpcode(), Op0BO->getOperand(0), Op1);
- NewShift->takeName(Op0BO);
-
- return BinaryOperator::Create(Op0BO->getOpcode(), NewShift,
- NewRHS);
- }
- }
- }
- }
-
- // Find out if this is a shift of a shift by a constant.
- BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0);
- if (ShiftOp && !ShiftOp->isShift())
- ShiftOp = 0;
-
- if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) {
- ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1));
- uint32_t ShiftAmt1 = ShiftAmt1C->getLimitedValue(TypeBits);
- uint32_t ShiftAmt2 = Op1->getLimitedValue(TypeBits);
- assert(ShiftAmt2 != 0 && "Should have been simplified earlier");
- if (ShiftAmt1 == 0) return 0; // Will be simplified in the future.
- Value *X = ShiftOp->getOperand(0);
-
- uint32_t AmtSum = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
-
- const IntegerType *Ty = cast<IntegerType>(I.getType());
-
- // Check for (X << c1) << c2 and (X >> c1) >> c2
- if (I.getOpcode() == ShiftOp->getOpcode()) {
- // If this is oversized composite shift, then unsigned shifts get 0, ashr
- // saturates.
- if (AmtSum >= TypeBits) {
- if (I.getOpcode() != Instruction::AShr)
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
- AmtSum = TypeBits-1; // Saturate to 31 for i32 ashr.
- }
-
- return BinaryOperator::Create(I.getOpcode(), X,
- ConstantInt::get(Ty, AmtSum));
- }
-
- if (ShiftOp->getOpcode() == Instruction::LShr &&
- I.getOpcode() == Instruction::AShr) {
- if (AmtSum >= TypeBits)
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
-
- // ((X >>u C1) >>s C2) -> (X >>u (C1+C2)) since C1 != 0.
- return BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, AmtSum));
- }
-
- if (ShiftOp->getOpcode() == Instruction::AShr &&
- I.getOpcode() == Instruction::LShr) {
- // ((X >>s C1) >>u C2) -> ((X >>s (C1+C2)) & mask) since C1 != 0.
- if (AmtSum >= TypeBits)
- AmtSum = TypeBits-1;
-
- Value *Shift = Builder->CreateAShr(X, ConstantInt::get(Ty, AmtSum));
-
- APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
- return BinaryOperator::CreateAnd(Shift, ConstantInt::get(*Context, Mask));
- }
-
- // Okay, if we get here, one shift must be left, and the other shift must be
- // right. See if the amounts are equal.
- if (ShiftAmt1 == ShiftAmt2) {
- // If we have ((X >>? C) << C), turn this into X & (-1 << C).
- if (I.getOpcode() == Instruction::Shl) {
- APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt1));
- return BinaryOperator::CreateAnd(X, ConstantInt::get(*Context, Mask));
- }
- // If we have ((X << C) >>u C), turn this into X & (-1 >>u C).
- if (I.getOpcode() == Instruction::LShr) {
- APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt1));
- return BinaryOperator::CreateAnd(X, ConstantInt::get(*Context, Mask));
- }
- // We can simplify ((X << C) >>s C) into a trunc + sext.
- // NOTE: we could do this for any C, but that would make 'unusual' integer
- // types. For now, just stick to ones well-supported by the code
- // generators.
- const Type *SExtType = 0;
- switch (Ty->getBitWidth() - ShiftAmt1) {
- case 1 :
- case 8 :
- case 16 :
- case 32 :
- case 64 :
- case 128:
- SExtType = IntegerType::get(*Context, Ty->getBitWidth() - ShiftAmt1);
- break;
- default: break;
- }
- if (SExtType)
- return new SExtInst(Builder->CreateTrunc(X, SExtType, "sext"), Ty);
- // Otherwise, we can't handle it yet.
- } else if (ShiftAmt1 < ShiftAmt2) {
- uint32_t ShiftDiff = ShiftAmt2-ShiftAmt1;
-
- // (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)
- if (I.getOpcode() == Instruction::Shl) {
- assert(ShiftOp->getOpcode() == Instruction::LShr ||
- ShiftOp->getOpcode() == Instruction::AShr);
- Value *Shift = Builder->CreateShl(X, ConstantInt::get(Ty, ShiftDiff));
-
- APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
- return BinaryOperator::CreateAnd(Shift,
- ConstantInt::get(*Context, Mask));
- }
-
- // (X << C1) >>u C2 --> X >>u (C2-C1) & (-1 >> C2)
- if (I.getOpcode() == Instruction::LShr) {
- assert(ShiftOp->getOpcode() == Instruction::Shl);
- Value *Shift = Builder->CreateLShr(X, ConstantInt::get(Ty, ShiftDiff));
-
- APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
- return BinaryOperator::CreateAnd(Shift,
- ConstantInt::get(*Context, Mask));
- }
-
- // We can't handle (X << C1) >>s C2, it shifts arbitrary bits in.
- } else {
- assert(ShiftAmt2 < ShiftAmt1);
- uint32_t ShiftDiff = ShiftAmt1-ShiftAmt2;
-
- // (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)
- if (I.getOpcode() == Instruction::Shl) {
- assert(ShiftOp->getOpcode() == Instruction::LShr ||
- ShiftOp->getOpcode() == Instruction::AShr);
- Value *Shift = Builder->CreateBinOp(ShiftOp->getOpcode(), X,
- ConstantInt::get(Ty, ShiftDiff));
-
- APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
- return BinaryOperator::CreateAnd(Shift,
- ConstantInt::get(*Context, Mask));
- }
-
- // (X << C1) >>u C2 --> X << (C1-C2) & (-1 >> C2)
- if (I.getOpcode() == Instruction::LShr) {
- assert(ShiftOp->getOpcode() == Instruction::Shl);
- Value *Shift = Builder->CreateShl(X, ConstantInt::get(Ty, ShiftDiff));
-
- APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
- return BinaryOperator::CreateAnd(Shift,
- ConstantInt::get(*Context, Mask));
- }
-
- // We can't handle (X << C1) >>a C2, it shifts arbitrary bits in.
- }
- }
- return 0;
-}
-
-
-/// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
-/// expression. If so, decompose it, returning some value X, such that Val is
-/// X*Scale+Offset.
-///
-static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
- int &Offset, LLVMContext *Context) {
- assert(Val->getType() == Type::getInt32Ty(*Context) &&
- "Unexpected allocation size type!");
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
- Offset = CI->getZExtValue();
- Scale = 0;
- return ConstantInt::get(Type::getInt32Ty(*Context), 0);
- } else if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
- if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
- if (I->getOpcode() == Instruction::Shl) {
- // This is a value scaled by '1 << the shift amt'.
- Scale = 1U << RHS->getZExtValue();
- Offset = 0;
- return I->getOperand(0);
- } else if (I->getOpcode() == Instruction::Mul) {
- // This value is scaled by 'RHS'.
- Scale = RHS->getZExtValue();
- Offset = 0;
- return I->getOperand(0);
- } else if (I->getOpcode() == Instruction::Add) {
- // We have X+C. Check to see if we really have (X*C2)+C1,
- // where C1 is divisible by C2.
- unsigned SubScale;
- Value *SubVal =
- DecomposeSimpleLinearExpr(I->getOperand(0), SubScale,
- Offset, Context);
- Offset += RHS->getZExtValue();
- Scale = SubScale;
- return SubVal;
- }
- }
- }
-
- // Otherwise, we can't look past this.
- Scale = 1;
- Offset = 0;
- return Val;
-}
-
-
-/// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
-/// try to eliminate the cast by moving the type information into the alloc.
-Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
- AllocaInst &AI) {
- const PointerType *PTy = cast<PointerType>(CI.getType());
-
- BuilderTy AllocaBuilder(*Builder);
- AllocaBuilder.SetInsertPoint(AI.getParent(), &AI);
-
- // Remove any uses of AI that are dead.
- assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
-
- for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
- Instruction *User = cast<Instruction>(*UI++);
- if (isInstructionTriviallyDead(User)) {
- while (UI != E && *UI == User)
- ++UI; // If this instruction uses AI more than once, don't break UI.
-
- ++NumDeadInst;
- DEBUG(errs() << "IC: DCE: " << *User << '\n');
- EraseInstFromFunction(*User);
- }
- }
-
- // This requires TargetData to get the alloca alignment and size information.
- if (!TD) return 0;
-
- // Get the type really allocated and the type casted to.
- const Type *AllocElTy = AI.getAllocatedType();
- const Type *CastElTy = PTy->getElementType();
- if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
-
- unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy);
- unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy);
- if (CastElTyAlign < AllocElTyAlign) return 0;
-
- // If the allocation has multiple uses, only promote it if we are strictly
- // increasing the alignment of the resultant allocation. If we keep it the
- // same, we open the door to infinite loops of various kinds. (A reference
- // from a dbg.declare doesn't count as a use for this purpose.)
- if (!AI.hasOneUse() && !hasOneUsePlusDeclare(&AI) &&
- CastElTyAlign == AllocElTyAlign) return 0;
-
- uint64_t AllocElTySize = TD->getTypeAllocSize(AllocElTy);
- uint64_t CastElTySize = TD->getTypeAllocSize(CastElTy);
- if (CastElTySize == 0 || AllocElTySize == 0) return 0;
-
- // See if we can satisfy the modulus by pulling a scale out of the array
- // size argument.
- unsigned ArraySizeScale;
- int ArrayOffset;
- Value *NumElements = // See if the array size is a decomposable linear expr.
- DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale,
- ArrayOffset, Context);
-
- // If we can now satisfy the modulus, by using a non-1 scale, we really can
- // do the xform.
- if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
- (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
-
- unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
- Value *Amt = 0;
- if (Scale == 1) {
- Amt = NumElements;
- } else {
- Amt = ConstantInt::get(Type::getInt32Ty(*Context), Scale);
- // Insert before the alloca, not before the cast.
- Amt = AllocaBuilder.CreateMul(Amt, NumElements, "tmp");
- }
-
- if (int Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
- Value *Off = ConstantInt::get(Type::getInt32Ty(*Context), Offset, true);
- Amt = AllocaBuilder.CreateAdd(Amt, Off, "tmp");
- }
-
- AllocaInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt);
- New->setAlignment(AI.getAlignment());
- New->takeName(&AI);
-
- // If the allocation has one real use plus a dbg.declare, just remove the
- // declare.
- if (DbgDeclareInst *DI = hasOneUsePlusDeclare(&AI)) {
- EraseInstFromFunction(*DI);
- }
- // If the allocation has multiple real uses, insert a cast and change all
- // things that used it to use the new cast. This will also hack on CI, but it
- // will die soon.
- else if (!AI.hasOneUse()) {
- // New is the allocation instruction, pointer typed. AI is the original
- // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
- Value *NewCast = AllocaBuilder.CreateBitCast(New, AI.getType(), "tmpcast");
- AI.replaceAllUsesWith(NewCast);
- }
- return ReplaceInstUsesWith(CI, New);
-}
-
-/// CanEvaluateInDifferentType - Return true if we can take the specified value
-/// and return it as type Ty without inserting any new casts and without
-/// changing the computed value. This is used by code that tries to decide
-/// whether promoting or shrinking integer operations to wider or smaller types
-/// will allow us to eliminate a truncate or extend.
-///
-/// This is a truncation operation if Ty is smaller than V->getType(), or an
-/// extension operation if Ty is larger.
-///
-/// If CastOpc is a truncation, then Ty will be a type smaller than V. We
-/// should return true if trunc(V) can be computed by computing V in the smaller
-/// type. If V is an instruction, then trunc(inst(x,y)) can be computed as
-/// inst(trunc(x),trunc(y)), which only makes sense if x and y can be
-/// efficiently truncated.
-///
-/// If CastOpc is a sext or zext, we are asking if the low bits of the value can
-/// bit computed in a larger type, which is then and'd or sext_in_reg'd to get
-/// the final result.
-bool InstCombiner::CanEvaluateInDifferentType(Value *V, const Type *Ty,
- unsigned CastOpc,
- int &NumCastsRemoved){
- // We can always evaluate constants in another type.
- if (isa<Constant>(V))
- return true;
-
- Instruction *I = dyn_cast<Instruction>(V);
- if (!I) return false;
-
- const Type *OrigTy = V->getType();
-
- // If this is an extension or truncate, we can often eliminate it.
- if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) {
- // If this is a cast from the destination type, we can trivially eliminate
- // it, and this will remove a cast overall.
- if (I->getOperand(0)->getType() == Ty) {
- // If the first operand is itself a cast, and is eliminable, do not count
- // this as an eliminable cast. We would prefer to eliminate those two
- // casts first.
- if (!isa<CastInst>(I->getOperand(0)) && I->hasOneUse())
- ++NumCastsRemoved;
- return true;
- }
- }
-
- // We can't extend or shrink something that has multiple uses: doing so would
- // require duplicating the instruction in general, which isn't profitable.
- if (!I->hasOneUse()) return false;
-
- unsigned Opc = I->getOpcode();
- switch (Opc) {
- case Instruction::Add:
- case Instruction::Sub:
- case Instruction::Mul:
- case Instruction::And:
- case Instruction::Or:
- case Instruction::Xor:
- // These operators can all arbitrarily be extended or truncated.
- return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
- NumCastsRemoved) &&
- CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
- NumCastsRemoved);
-
- case Instruction::UDiv:
- case Instruction::URem: {
- // UDiv and URem can be truncated if all the truncated bits are zero.
- uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
- uint32_t BitWidth = Ty->getScalarSizeInBits();
- if (BitWidth < OrigBitWidth) {
- APInt Mask = APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth);
- if (MaskedValueIsZero(I->getOperand(0), Mask) &&
- MaskedValueIsZero(I->getOperand(1), Mask)) {
- return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
- NumCastsRemoved) &&
- CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
- NumCastsRemoved);
- }
- }
- break;
- }
- case Instruction::Shl:
- // If we are truncating the result of this SHL, and if it's a shift of a
- // constant amount, we can always perform a SHL in a smaller type.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
- uint32_t BitWidth = Ty->getScalarSizeInBits();
- if (BitWidth < OrigTy->getScalarSizeInBits() &&
- CI->getLimitedValue(BitWidth) < BitWidth)
- return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
- NumCastsRemoved);
- }
- break;
- case Instruction::LShr:
- // If this is a truncate of a logical shr, we can truncate it to a smaller
- // lshr iff we know that the bits we would otherwise be shifting in are
- // already zeros.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
- uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
- uint32_t BitWidth = Ty->getScalarSizeInBits();
- if (BitWidth < OrigBitWidth &&
- MaskedValueIsZero(I->getOperand(0),
- APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
- CI->getLimitedValue(BitWidth) < BitWidth) {
- return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
- NumCastsRemoved);
- }
- }
- break;
- case Instruction::ZExt:
- case Instruction::SExt:
- case Instruction::Trunc:
- // If this is the same kind of case as our original (e.g. zext+zext), we
- // can safely replace it. Note that replacing it does not reduce the number
- // of casts in the input.
- if (Opc == CastOpc)
- return true;
-
- // sext (zext ty1), ty2 -> zext ty2
- if (CastOpc == Instruction::SExt && Opc == Instruction::ZExt)
- return true;
- break;
- case Instruction::Select: {
- SelectInst *SI = cast<SelectInst>(I);
- return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc,
- NumCastsRemoved) &&
- CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc,
- NumCastsRemoved);
- }
- case Instruction::PHI: {
- // We can change a phi if we can change all operands.
- PHINode *PN = cast<PHINode>(I);
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
- if (!CanEvaluateInDifferentType(PN->getIncomingValue(i), Ty, CastOpc,
- NumCastsRemoved))
- return false;
- return true;
- }
- default:
- // TODO: Can handle more cases here.
- break;
- }
-
- return false;
-}
-
-/// EvaluateInDifferentType - Given an expression that
-/// CanEvaluateInDifferentType returns true for, actually insert the code to
-/// evaluate the expression.
-Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
- bool isSigned) {
- if (Constant *C = dyn_cast<Constant>(V))
- return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
-
- // Otherwise, it must be an instruction.
- Instruction *I = cast<Instruction>(V);
- Instruction *Res = 0;
- unsigned Opc = I->getOpcode();
- switch (Opc) {
- case Instruction::Add:
- case Instruction::Sub:
- case Instruction::Mul:
- case Instruction::And:
- case Instruction::Or:
- case Instruction::Xor:
- case Instruction::AShr:
- case Instruction::LShr:
- case Instruction::Shl:
- case Instruction::UDiv:
- case Instruction::URem: {
- Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
- Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
- Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
- break;
- }
- case Instruction::Trunc:
- case Instruction::ZExt:
- case Instruction::SExt:
- // If the source type of the cast is the type we're trying for then we can
- // just return the source. There's no need to insert it because it is not
- // new.
- if (I->getOperand(0)->getType() == Ty)
- return I->getOperand(0);
-
- // Otherwise, must be the same type of cast, so just reinsert a new one.
- Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),Ty);
- break;
- case Instruction::Select: {
- Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
- Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
- Res = SelectInst::Create(I->getOperand(0), True, False);
- break;
- }
- case Instruction::PHI: {
- PHINode *OPN = cast<PHINode>(I);
- PHINode *NPN = PHINode::Create(Ty);
- for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
- Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
- NPN->addIncoming(V, OPN->getIncomingBlock(i));
- }
- Res = NPN;
- break;
- }
- default:
- // TODO: Can handle more cases here.
- llvm_unreachable("Unreachable!");
- break;
- }
-
- Res->takeName(I);
- return InsertNewInstBefore(Res, *I);
-}
-
-/// @brief Implement the transforms common to all CastInst visitors.
-Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
- Value *Src = CI.getOperand(0);
-
- // Many cases of "cast of a cast" are eliminable. If it's eliminable we just
- // eliminate it now.
- if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
- if (Instruction::CastOps opc =
- isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) {
- // The first cast (CSrc) is eliminable so we need to fix up or replace
- // the second cast (CI). CSrc will then have a good chance of being dead.
- return CastInst::Create(opc, CSrc->getOperand(0), CI.getType());
- }
- }
-
- // If we are casting a select then fold the cast into the select
- if (SelectInst *SI = dyn_cast<SelectInst>(Src))
- if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
- return NV;
-
- // If we are casting a PHI then fold the cast into the PHI
- if (isa<PHINode>(Src)) {
- // We don't do this if this would create a PHI node with an illegal type if
- // it is currently legal.
- if (!isa<IntegerType>(Src->getType()) ||
- !isa<IntegerType>(CI.getType()) ||
- ShouldChangeType(CI.getType(), Src->getType(), TD))
- if (Instruction *NV = FoldOpIntoPhi(CI))
- return NV;
- }
-
- return 0;
-}
-
-/// FindElementAtOffset - Given a type and a constant offset, determine whether
-/// or not there is a sequence of GEP indices into the type that will land us at
-/// the specified offset. If so, fill them into NewIndices and return the
-/// resultant element type, otherwise return null.
-static const Type *FindElementAtOffset(const Type *Ty, int64_t Offset,
- SmallVectorImpl<Value*> &NewIndices,
- const TargetData *TD,
- LLVMContext *Context) {
- if (!TD) return 0;
- if (!Ty->isSized()) return 0;
-
- // Start with the index over the outer type. Note that the type size
- // might be zero (even if the offset isn't zero) if the indexed type
- // is something like [0 x {int, int}]
- const Type *IntPtrTy = TD->getIntPtrType(*Context);
- int64_t FirstIdx = 0;
- if (int64_t TySize = TD->getTypeAllocSize(Ty)) {
- FirstIdx = Offset/TySize;
- Offset -= FirstIdx*TySize;
-
- // Handle hosts where % returns negative instead of values [0..TySize).
- if (Offset < 0) {
- --FirstIdx;
- Offset += TySize;
- assert(Offset >= 0);
- }
- assert((uint64_t)Offset < (uint64_t)TySize && "Out of range offset");
- }
-
- NewIndices.push_back(ConstantInt::get(IntPtrTy, FirstIdx));
-
- // Index into the types. If we fail, set OrigBase to null.
- while (Offset) {
- // Indexing into tail padding between struct/array elements.
- if (uint64_t(Offset*8) >= TD->getTypeSizeInBits(Ty))
- return 0;
-
- if (const StructType *STy = dyn_cast<StructType>(Ty)) {
- const StructLayout *SL = TD->getStructLayout(STy);
- assert(Offset < (int64_t)SL->getSizeInBytes() &&
- "Offset must stay within the indexed type");
-
- unsigned Elt = SL->getElementContainingOffset(Offset);
- NewIndices.push_back(ConstantInt::get(Type::getInt32Ty(*Context), Elt));
-
- Offset -= SL->getElementOffset(Elt);
- Ty = STy->getElementType(Elt);
- } else if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
- uint64_t EltSize = TD->getTypeAllocSize(AT->getElementType());
- assert(EltSize && "Cannot index into a zero-sized array");
- NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize));
- Offset %= EltSize;
- Ty = AT->getElementType();
- } else {
- // Otherwise, we can't index into the middle of this atomic type, bail.
- return 0;
- }
- }
-
- return Ty;
-}
-
-/// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint)
-Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
- Value *Src = CI.getOperand(0);
-
- if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
- // If casting the result of a getelementptr instruction with no offset, turn
- // this into a cast of the original pointer!
- if (GEP->hasAllZeroIndices()) {
- // Changing the cast operand is usually not a good idea but it is safe
- // here because the pointer operand is being replaced with another
- // pointer operand so the opcode doesn't need to change.
- Worklist.Add(GEP);
- CI.setOperand(0, GEP->getOperand(0));
- return &CI;
- }
-
- // If the GEP has a single use, and the base pointer is a bitcast, and the
- // GEP computes a constant offset, see if we can convert these three
- // instructions into fewer. This typically happens with unions and other
- // non-type-safe code.
- if (TD && GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0))) {
- if (GEP->hasAllConstantIndices()) {
- // We are guaranteed to get a constant from EmitGEPOffset.
- ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP, *this));
- int64_t Offset = OffsetV->getSExtValue();
-
- // Get the base pointer input of the bitcast, and the type it points to.
- Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0);
- const Type *GEPIdxTy =
- cast<PointerType>(OrigBase->getType())->getElementType();
- SmallVector<Value*, 8> NewIndices;
- if (FindElementAtOffset(GEPIdxTy, Offset, NewIndices, TD, Context)) {
- // If we were able to index down into an element, create the GEP
- // and bitcast the result. This eliminates one bitcast, potentially
- // two.
- Value *NGEP = cast<GEPOperator>(GEP)->isInBounds() ?
- Builder->CreateInBoundsGEP(OrigBase,
- NewIndices.begin(), NewIndices.end()) :
- Builder->CreateGEP(OrigBase, NewIndices.begin(), NewIndices.end());
- NGEP->takeName(GEP);
-
- if (isa<BitCastInst>(CI))
- return new BitCastInst(NGEP, CI.getType());
- assert(isa<PtrToIntInst>(CI));
- return new PtrToIntInst(NGEP, CI.getType());
- }
- }
- }
- }
-
- return commonCastTransforms(CI);
-}
-
-/// commonIntCastTransforms - This function implements the common transforms
-/// for trunc, zext, and sext.
-Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
- if (Instruction *Result = commonCastTransforms(CI))
- return Result;
-
- Value *Src = CI.getOperand(0);
- const Type *SrcTy = Src->getType();
- const Type *DestTy = CI.getType();
- uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
- uint32_t DestBitSize = DestTy->getScalarSizeInBits();
-
- // See if we can simplify any instructions used by the LHS whose sole
- // purpose is to compute bits we don't care about.
- if (SimplifyDemandedInstructionBits(CI))
- return &CI;
-
- // If the source isn't an instruction or has more than one use then we
- // can't do anything more.
- Instruction *SrcI = dyn_cast<Instruction>(Src);
- if (!SrcI || !Src->hasOneUse())
- return 0;
-
- // Attempt to propagate the cast into the instruction for int->int casts.
- int NumCastsRemoved = 0;
- // Only do this if the dest type is a simple type, don't convert the
- // expression tree to something weird like i93 unless the source is also
- // strange.
- if ((isa<VectorType>(DestTy) ||
- ShouldChangeType(SrcI->getType(), DestTy, TD)) &&
- CanEvaluateInDifferentType(SrcI, DestTy,
- CI.getOpcode(), NumCastsRemoved)) {
- // If this cast is a truncate, evaluting in a different type always
- // eliminates the cast, so it is always a win. If this is a zero-extension,
- // we need to do an AND to maintain the clear top-part of the computation,
- // so we require that the input have eliminated at least one cast. If this
- // is a sign extension, we insert two new casts (to do the extension) so we
- // require that two casts have been eliminated.
- bool DoXForm = false;
- bool JustReplace = false;
- switch (CI.getOpcode()) {
- default:
- // All the others use floating point so we shouldn't actually
- // get here because of the check above.
- llvm_unreachable("Unknown cast type");
- case Instruction::Trunc:
- DoXForm = true;
- break;
- case Instruction::ZExt: {
- DoXForm = NumCastsRemoved >= 1;
-
- if (!DoXForm && 0) {
- // If it's unnecessary to issue an AND to clear the high bits, it's
- // always profitable to do this xform.
- Value *TryRes = EvaluateInDifferentType(SrcI, DestTy, false);
- APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
- if (MaskedValueIsZero(TryRes, Mask))
- return ReplaceInstUsesWith(CI, TryRes);
-
- if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
- if (TryI->use_empty())
- EraseInstFromFunction(*TryI);
- }
- break;
- }
- case Instruction::SExt: {
- DoXForm = NumCastsRemoved >= 2;
- if (!DoXForm && !isa<TruncInst>(SrcI) && 0) {
- // If we do not have to emit the truncate + sext pair, then it's always
- // profitable to do this xform.
- //
- // It's not safe to eliminate the trunc + sext pair if one of the
- // eliminated cast is a truncate. e.g.
- // t2 = trunc i32 t1 to i16
- // t3 = sext i16 t2 to i32
- // !=
- // i32 t1
- Value *TryRes = EvaluateInDifferentType(SrcI, DestTy, true);
- unsigned NumSignBits = ComputeNumSignBits(TryRes);
- if (NumSignBits > (DestBitSize - SrcBitSize))
- return ReplaceInstUsesWith(CI, TryRes);
-
- if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
- if (TryI->use_empty())
- EraseInstFromFunction(*TryI);
- }
- break;
- }
- }
-
- if (DoXForm) {
- DEBUG(errs() << "ICE: EvaluateInDifferentType converting expression type"
- " to avoid cast: " << CI);
- Value *Res = EvaluateInDifferentType(SrcI, DestTy,
- CI.getOpcode() == Instruction::SExt);
- if (JustReplace)
- // Just replace this cast with the result.
- return ReplaceInstUsesWith(CI, Res);
-
- assert(Res->getType() == DestTy);
- switch (CI.getOpcode()) {
- default: llvm_unreachable("Unknown cast type!");
- case Instruction::Trunc:
- // Just replace this cast with the result.
- return ReplaceInstUsesWith(CI, Res);
- case Instruction::ZExt: {
- assert(SrcBitSize < DestBitSize && "Not a zext?");
-
- // If the high bits are already zero, just replace this cast with the
- // result.
- APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
- if (MaskedValueIsZero(Res, Mask))
- return ReplaceInstUsesWith(CI, Res);
-
- // We need to emit an AND to clear the high bits.
- Constant *C = ConstantInt::get(*Context,
- APInt::getLowBitsSet(DestBitSize, SrcBitSize));
- return BinaryOperator::CreateAnd(Res, C);
- }
- case Instruction::SExt: {
- // If the high bits are already filled with sign bit, just replace this
- // cast with the result.
- unsigned NumSignBits = ComputeNumSignBits(Res);
- if (NumSignBits > (DestBitSize - SrcBitSize))
- return ReplaceInstUsesWith(CI, Res);
-
- // We need to emit a cast to truncate, then a cast to sext.
- return new SExtInst(Builder->CreateTrunc(Res, Src->getType()), DestTy);
- }
- }
- }
- }
-
- Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
- Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
-
- switch (SrcI->getOpcode()) {
- case Instruction::Add:
- case Instruction::Mul:
- case Instruction::And:
- case Instruction::Or:
- case Instruction::Xor:
- // If we are discarding information, rewrite.
- if (DestBitSize < SrcBitSize && DestBitSize != 1) {
- // Don't insert two casts unless at least one can be eliminated.
- if (!ValueRequiresCast(CI.getOpcode(), Op1, DestTy, TD) ||
- !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
- Value *Op0c = Builder->CreateTrunc(Op0, DestTy, Op0->getName());
- Value *Op1c = Builder->CreateTrunc(Op1, DestTy, Op1->getName());
- return BinaryOperator::Create(
- cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
- }
- }
-
- // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
- if (isa<ZExtInst>(CI) && SrcBitSize == 1 &&
- SrcI->getOpcode() == Instruction::Xor &&
- Op1 == ConstantInt::getTrue(*Context) &&
- (!Op0->hasOneUse() || !isa<CmpInst>(Op0))) {
- Value *New = Builder->CreateZExt(Op0, DestTy, Op0->getName());
- return BinaryOperator::CreateXor(New,
- ConstantInt::get(CI.getType(), 1));
- }
- break;
-
- case Instruction::Shl: {
- // Canonicalize trunc inside shl, if we can.
- ConstantInt *CI = dyn_cast<ConstantInt>(Op1);
- if (CI && DestBitSize < SrcBitSize &&
- CI->getLimitedValue(DestBitSize) < DestBitSize) {
- Value *Op0c = Builder->CreateTrunc(Op0, DestTy, Op0->getName());
- Value *Op1c = Builder->CreateTrunc(Op1, DestTy, Op1->getName());
- return BinaryOperator::CreateShl(Op0c, Op1c);
- }
- break;
- }
- }
- return 0;
-}
-
-Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
- if (Instruction *Result = commonIntCastTransforms(CI))
- return Result;
-
- Value *Src = CI.getOperand(0);
- const Type *Ty = CI.getType();
- uint32_t DestBitWidth = Ty->getScalarSizeInBits();
- uint32_t SrcBitWidth = Src->getType()->getScalarSizeInBits();
-
- // Canonicalize trunc x to i1 -> (icmp ne (and x, 1), 0)
- if (DestBitWidth == 1) {
- Constant *One = ConstantInt::get(Src->getType(), 1);
- Src = Builder->CreateAnd(Src, One, "tmp");
- Value *Zero = Constant::getNullValue(Src->getType());
- return new ICmpInst(ICmpInst::ICMP_NE, Src, Zero);
- }
-
- // Optimize trunc(lshr(), c) to pull the shift through the truncate.
- ConstantInt *ShAmtV = 0;
- Value *ShiftOp = 0;
- if (Src->hasOneUse() &&
- match(Src, m_LShr(m_Value(ShiftOp), m_ConstantInt(ShAmtV)))) {
- uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth);
-
- // Get a mask for the bits shifting in.
- APInt Mask(APInt::getLowBitsSet(SrcBitWidth, ShAmt).shl(DestBitWidth));
- if (MaskedValueIsZero(ShiftOp, Mask)) {
- if (ShAmt >= DestBitWidth) // All zeros.
- return ReplaceInstUsesWith(CI, Constant::getNullValue(Ty));
-
- // Okay, we can shrink this. Truncate the input, then return a new
- // shift.
- Value *V1 = Builder->CreateTrunc(ShiftOp, Ty, ShiftOp->getName());
- Value *V2 = ConstantExpr::getTrunc(ShAmtV, Ty);
- return BinaryOperator::CreateLShr(V1, V2);
- }
- }
-
- return 0;
-}
-
-/// transformZExtICmp - Transform (zext icmp) to bitwise / integer operations
-/// in order to eliminate the icmp.
-Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI,
- bool DoXform) {
- // If we are just checking for a icmp eq of a single bit and zext'ing it
- // to an integer, then shift the bit to the appropriate place and then
- // cast to integer to avoid the comparison.
- if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
- const APInt &Op1CV = Op1C->getValue();
-
- // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
- // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
- if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
- (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) {
- if (!DoXform) return ICI;
-
- Value *In = ICI->getOperand(0);
- Value *Sh = ConstantInt::get(In->getType(),
- In->getType()->getScalarSizeInBits()-1);
- In = Builder->CreateLShr(In, Sh, In->getName()+".lobit");
- if (In->getType() != CI.getType())
- In = Builder->CreateIntCast(In, CI.getType(), false/*ZExt*/, "tmp");
-
- if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
- Constant *One = ConstantInt::get(In->getType(), 1);
- In = Builder->CreateXor(In, One, In->getName()+".not");
- }
-
- return ReplaceInstUsesWith(CI, In);
- }
-
-
-
- // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
- // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
- // zext (X == 1) to i32 --> X iff X has only the low bit set.
- // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
- // zext (X != 0) to i32 --> X iff X has only the low bit set.
- // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
- // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
- // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
- if ((Op1CV == 0 || Op1CV.isPowerOf2()) &&
- // This only works for EQ and NE
- ICI->isEquality()) {
- // If Op1C some other power of two, convert:
- uint32_t BitWidth = Op1C->getType()->getBitWidth();
- APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
- APInt TypeMask(APInt::getAllOnesValue(BitWidth));
- ComputeMaskedBits(ICI->getOperand(0), TypeMask, KnownZero, KnownOne);
-
- APInt KnownZeroMask(~KnownZero);
- if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
- if (!DoXform) return ICI;
-
- bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
- if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
- // (X&4) == 2 --> false
- // (X&4) != 2 --> true
- Constant *Res = ConstantInt::get(Type::getInt1Ty(*Context), isNE);
- Res = ConstantExpr::getZExt(Res, CI.getType());
- return ReplaceInstUsesWith(CI, Res);
- }
-
- uint32_t ShiftAmt = KnownZeroMask.logBase2();
- Value *In = ICI->getOperand(0);
- if (ShiftAmt) {
- // Perform a logical shr by shiftamt.
- // Insert the shift to put the result in the low bit.
- In = Builder->CreateLShr(In, ConstantInt::get(In->getType(),ShiftAmt),
- In->getName()+".lobit");
- }
-
- if ((Op1CV != 0) == isNE) { // Toggle the low bit.
- Constant *One = ConstantInt::get(In->getType(), 1);
- In = Builder->CreateXor(In, One, "tmp");
- }
-
- if (CI.getType() == In->getType())
- return ReplaceInstUsesWith(CI, In);
- else
- return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/);
- }
- }
- }
-
- // icmp ne A, B is equal to xor A, B when A and B only really have one bit.
- // It is also profitable to transform icmp eq into not(xor(A, B)) because that
- // may lead to additional simplifications.
- if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) {
- if (const IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) {
- uint32_t BitWidth = ITy->getBitWidth();
- Value *LHS = ICI->getOperand(0);
- Value *RHS = ICI->getOperand(1);
-
- APInt KnownZeroLHS(BitWidth, 0), KnownOneLHS(BitWidth, 0);
- APInt KnownZeroRHS(BitWidth, 0), KnownOneRHS(BitWidth, 0);
- APInt TypeMask(APInt::getAllOnesValue(BitWidth));
- ComputeMaskedBits(LHS, TypeMask, KnownZeroLHS, KnownOneLHS);
- ComputeMaskedBits(RHS, TypeMask, KnownZeroRHS, KnownOneRHS);
-
- if (KnownZeroLHS == KnownZeroRHS && KnownOneLHS == KnownOneRHS) {
- APInt KnownBits = KnownZeroLHS | KnownOneLHS;
- APInt UnknownBit = ~KnownBits;
- if (UnknownBit.countPopulation() == 1) {
- if (!DoXform) return ICI;
-
- Value *Result = Builder->CreateXor(LHS, RHS);
-
- // Mask off any bits that are set and won't be shifted away.
- if (KnownOneLHS.uge(UnknownBit))
- Result = Builder->CreateAnd(Result,
- ConstantInt::get(ITy, UnknownBit));
-
- // Shift the bit we're testing down to the lsb.
- Result = Builder->CreateLShr(
- Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros()));
-
- if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
- Result = Builder->CreateXor(Result, ConstantInt::get(ITy, 1));
- Result->takeName(ICI);
- return ReplaceInstUsesWith(CI, Result);
- }
- }
- }
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
- // If one of the common conversion will work ..
- if (Instruction *Result = commonIntCastTransforms(CI))
- return Result;
-
- Value *Src = CI.getOperand(0);
-
- // If this is a TRUNC followed by a ZEXT then we are dealing with integral
- // types and if the sizes are just right we can convert this into a logical
- // 'and' which will be much cheaper than the pair of casts.
- if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast
- // Get the sizes of the types involved. We know that the intermediate type
- // will be smaller than A or C, but don't know the relation between A and C.
- Value *A = CSrc->getOperand(0);
- unsigned SrcSize = A->getType()->getScalarSizeInBits();
- unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
- unsigned DstSize = CI.getType()->getScalarSizeInBits();
- // If we're actually extending zero bits, then if
- // SrcSize < DstSize: zext(a & mask)
- // SrcSize == DstSize: a & mask
- // SrcSize > DstSize: trunc(a) & mask
- if (SrcSize < DstSize) {
- APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
- Constant *AndConst = ConstantInt::get(A->getType(), AndValue);
- Value *And = Builder->CreateAnd(A, AndConst, CSrc->getName()+".mask");
- return new ZExtInst(And, CI.getType());
- }
-
- if (SrcSize == DstSize) {
- APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
- return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(),
- AndValue));
- }
- if (SrcSize > DstSize) {
- Value *Trunc = Builder->CreateTrunc(A, CI.getType(), "tmp");
- APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
- return BinaryOperator::CreateAnd(Trunc,
- ConstantInt::get(Trunc->getType(),
- AndValue));
- }
- }
-
- if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
- return transformZExtICmp(ICI, CI);
-
- BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
- if (SrcI && SrcI->getOpcode() == Instruction::Or) {
- // zext (or icmp, icmp) --> or (zext icmp), (zext icmp) if at least one
- // of the (zext icmp) will be transformed.
- ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
- ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
- if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
- (transformZExtICmp(LHS, CI, false) ||
- transformZExtICmp(RHS, CI, false))) {
- Value *LCast = Builder->CreateZExt(LHS, CI.getType(), LHS->getName());
- Value *RCast = Builder->CreateZExt(RHS, CI.getType(), RHS->getName());
- return BinaryOperator::Create(Instruction::Or, LCast, RCast);
- }
- }
-
- // zext(trunc(t) & C) -> (t & zext(C)).
- if (SrcI && SrcI->getOpcode() == Instruction::And && SrcI->hasOneUse())
- if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
- if (TruncInst *TI = dyn_cast<TruncInst>(SrcI->getOperand(0))) {
- Value *TI0 = TI->getOperand(0);
- if (TI0->getType() == CI.getType())
- return
- BinaryOperator::CreateAnd(TI0,
- ConstantExpr::getZExt(C, CI.getType()));
- }
-
- // zext((trunc(t) & C) ^ C) -> ((t & zext(C)) ^ zext(C)).
- if (SrcI && SrcI->getOpcode() == Instruction::Xor && SrcI->hasOneUse())
- if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
- if (BinaryOperator *And = dyn_cast<BinaryOperator>(SrcI->getOperand(0)))
- if (And->getOpcode() == Instruction::And && And->hasOneUse() &&
- And->getOperand(1) == C)
- if (TruncInst *TI = dyn_cast<TruncInst>(And->getOperand(0))) {
- Value *TI0 = TI->getOperand(0);
- if (TI0->getType() == CI.getType()) {
- Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
- Value *NewAnd = Builder->CreateAnd(TI0, ZC, "tmp");
- return BinaryOperator::CreateXor(NewAnd, ZC);
- }
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitSExt(SExtInst &CI) {
- if (Instruction *I = commonIntCastTransforms(CI))
- return I;
-
- Value *Src = CI.getOperand(0);
-
- // Canonicalize sign-extend from i1 to a select.
- if (Src->getType() == Type::getInt1Ty(*Context))
- return SelectInst::Create(Src,
- Constant::getAllOnesValue(CI.getType()),
- Constant::getNullValue(CI.getType()));
-
- // See if the value being truncated is already sign extended. If so, just
- // eliminate the trunc/sext pair.
- if (Operator::getOpcode(Src) == Instruction::Trunc) {
- Value *Op = cast<User>(Src)->getOperand(0);
- unsigned OpBits = Op->getType()->getScalarSizeInBits();
- unsigned MidBits = Src->getType()->getScalarSizeInBits();
- unsigned DestBits = CI.getType()->getScalarSizeInBits();
- unsigned NumSignBits = ComputeNumSignBits(Op);
-
- if (OpBits == DestBits) {
- // Op is i32, Mid is i8, and Dest is i32. If Op has more than 24 sign
- // bits, it is already ready.
- if (NumSignBits > DestBits-MidBits)
- return ReplaceInstUsesWith(CI, Op);
- } else if (OpBits < DestBits) {
- // Op is i32, Mid is i8, and Dest is i64. If Op has more than 24 sign
- // bits, just sext from i32.
- if (NumSignBits > OpBits-MidBits)
- return new SExtInst(Op, CI.getType(), "tmp");
- } else {
- // Op is i64, Mid is i8, and Dest is i32. If Op has more than 56 sign
- // bits, just truncate to i32.
- if (NumSignBits > OpBits-MidBits)
- return new TruncInst(Op, CI.getType(), "tmp");
- }
- }
-
- // If the input is a shl/ashr pair of a same constant, then this is a sign
- // extension from a smaller value. If we could trust arbitrary bitwidth
- // integers, we could turn this into a truncate to the smaller bit and then
- // use a sext for the whole extension. Since we don't, look deeper and check
- // for a truncate. If the source and dest are the same type, eliminate the
- // trunc and extend and just do shifts. For example, turn:
- // %a = trunc i32 %i to i8
- // %b = shl i8 %a, 6
- // %c = ashr i8 %b, 6
- // %d = sext i8 %c to i32
- // into:
- // %a = shl i32 %i, 30
- // %d = ashr i32 %a, 30
- Value *A = 0;
- ConstantInt *BA = 0, *CA = 0;
- if (match(Src, m_AShr(m_Shl(m_Value(A), m_ConstantInt(BA)),
- m_ConstantInt(CA))) &&
- BA == CA && isa<TruncInst>(A)) {
- Value *I = cast<TruncInst>(A)->getOperand(0);
- if (I->getType() == CI.getType()) {
- unsigned MidSize = Src->getType()->getScalarSizeInBits();
- unsigned SrcDstSize = CI.getType()->getScalarSizeInBits();
- unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
- Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
- I = Builder->CreateShl(I, ShAmtV, CI.getName());
- return BinaryOperator::CreateAShr(I, ShAmtV);
- }
- }
-
- return 0;
-}
-
-/// FitsInFPType - Return a Constant* for the specified FP constant if it fits
-/// in the specified FP type without changing its value.
-static Constant *FitsInFPType(ConstantFP *CFP, const fltSemantics &Sem,
- LLVMContext *Context) {
- bool losesInfo;
- APFloat F = CFP->getValueAPF();
- (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
- if (!losesInfo)
- return ConstantFP::get(*Context, F);
- return 0;
-}
-
-/// LookThroughFPExtensions - If this is an fp extension instruction, look
-/// through it until we get the source value.
-static Value *LookThroughFPExtensions(Value *V, LLVMContext *Context) {
- if (Instruction *I = dyn_cast<Instruction>(V))
- if (I->getOpcode() == Instruction::FPExt)
- return LookThroughFPExtensions(I->getOperand(0), Context);
-
- // If this value is a constant, return the constant in the smallest FP type
- // that can accurately represent it. This allows us to turn
- // (float)((double)X+2.0) into x+2.0f.
- if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
- if (CFP->getType() == Type::getPPC_FP128Ty(*Context))
- return V; // No constant folding of this.
- // See if the value can be truncated to float and then reextended.
- if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle, Context))
- return V;
- if (CFP->getType() == Type::getDoubleTy(*Context))
- return V; // Won't shrink.
- if (Value *V = FitsInFPType(CFP, APFloat::IEEEdouble, Context))
- return V;
- // Don't try to shrink to various long double types.
- }
-
- return V;
-}
-
-Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) {
- if (Instruction *I = commonCastTransforms(CI))
- return I;
-
- // If we have fptrunc(fadd (fpextend x), (fpextend y)), where x and y are
- // smaller than the destination type, we can eliminate the truncate by doing
- // the add as the smaller type. This applies to fadd/fsub/fmul/fdiv as well as
- // many builtins (sqrt, etc).
- BinaryOperator *OpI = dyn_cast<BinaryOperator>(CI.getOperand(0));
- if (OpI && OpI->hasOneUse()) {
- switch (OpI->getOpcode()) {
- default: break;
- case Instruction::FAdd:
- case Instruction::FSub:
- case Instruction::FMul:
- case Instruction::FDiv:
- case Instruction::FRem:
- const Type *SrcTy = OpI->getType();
- Value *LHSTrunc = LookThroughFPExtensions(OpI->getOperand(0), Context);
- Value *RHSTrunc = LookThroughFPExtensions(OpI->getOperand(1), Context);
- if (LHSTrunc->getType() != SrcTy &&
- RHSTrunc->getType() != SrcTy) {
- unsigned DstSize = CI.getType()->getScalarSizeInBits();
- // If the source types were both smaller than the destination type of
- // the cast, do this xform.
- if (LHSTrunc->getType()->getScalarSizeInBits() <= DstSize &&
- RHSTrunc->getType()->getScalarSizeInBits() <= DstSize) {
- LHSTrunc = Builder->CreateFPExt(LHSTrunc, CI.getType());
- RHSTrunc = Builder->CreateFPExt(RHSTrunc, CI.getType());
- return BinaryOperator::Create(OpI->getOpcode(), LHSTrunc, RHSTrunc);
- }
- }
- break;
- }
- }
- return 0;
-}
-
-Instruction *InstCombiner::visitFPExt(CastInst &CI) {
- return commonCastTransforms(CI);
-}
-
-Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
- Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
- if (OpI == 0)
- return commonCastTransforms(FI);
-
- // fptoui(uitofp(X)) --> X
- // fptoui(sitofp(X)) --> X
- // This is safe if the intermediate type has enough bits in its mantissa to
- // accurately represent all values of X. For example, do not do this with
- // i64->float->i64. This is also safe for sitofp case, because any negative
- // 'X' value would cause an undefined result for the fptoui.
- if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
- OpI->getOperand(0)->getType() == FI.getType() &&
- (int)FI.getType()->getScalarSizeInBits() < /*extra bit for sign */
- OpI->getType()->getFPMantissaWidth())
- return ReplaceInstUsesWith(FI, OpI->getOperand(0));
-
- return commonCastTransforms(FI);
-}
-
-Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
- Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
- if (OpI == 0)
- return commonCastTransforms(FI);
-
- // fptosi(sitofp(X)) --> X
- // fptosi(uitofp(X)) --> X
- // This is safe if the intermediate type has enough bits in its mantissa to
- // accurately represent all values of X. For example, do not do this with
- // i64->float->i64. This is also safe for sitofp case, because any negative
- // 'X' value would cause an undefined result for the fptoui.
- if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
- OpI->getOperand(0)->getType() == FI.getType() &&
- (int)FI.getType()->getScalarSizeInBits() <=
- OpI->getType()->getFPMantissaWidth())
- return ReplaceInstUsesWith(FI, OpI->getOperand(0));
-
- return commonCastTransforms(FI);
-}
-
-Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
- return commonCastTransforms(CI);
-}
-
-Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
- return commonCastTransforms(CI);
-}
-
-Instruction *InstCombiner::visitPtrToInt(PtrToIntInst &CI) {
- // If the destination integer type is smaller than the intptr_t type for
- // this target, do a ptrtoint to intptr_t then do a trunc. This allows the
- // trunc to be exposed to other transforms. Don't do this for extending
- // ptrtoint's, because we don't know if the target sign or zero extends its
- // pointers.
- if (TD &&
- CI.getType()->getScalarSizeInBits() < TD->getPointerSizeInBits()) {
- Value *P = Builder->CreatePtrToInt(CI.getOperand(0),
- TD->getIntPtrType(CI.getContext()),
- "tmp");
- return new TruncInst(P, CI.getType());
- }
-
- return commonPointerCastTransforms(CI);
-}
-
-Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) {
- // If the source integer type is larger than the intptr_t type for
- // this target, do a trunc to the intptr_t type, then inttoptr of it. This
- // allows the trunc to be exposed to other transforms. Don't do this for
- // extending inttoptr's, because we don't know if the target sign or zero
- // extends to pointers.
- if (TD && CI.getOperand(0)->getType()->getScalarSizeInBits() >
- TD->getPointerSizeInBits()) {
- Value *P = Builder->CreateTrunc(CI.getOperand(0),
- TD->getIntPtrType(CI.getContext()), "tmp");
- return new IntToPtrInst(P, CI.getType());
- }
-
- if (Instruction *I = commonCastTransforms(CI))
- return I;
-
- return 0;
-}
-
-Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
- // If the operands are integer typed then apply the integer transforms,
- // otherwise just apply the common ones.
- Value *Src = CI.getOperand(0);
- const Type *SrcTy = Src->getType();
- const Type *DestTy = CI.getType();
-
- if (isa<PointerType>(SrcTy)) {
- if (Instruction *I = commonPointerCastTransforms(CI))
- return I;
- } else {
- if (Instruction *Result = commonCastTransforms(CI))
- return Result;
- }
-
-
- // Get rid of casts from one type to the same type. These are useless and can
- // be replaced by the operand.
- if (DestTy == Src->getType())
- return ReplaceInstUsesWith(CI, Src);
-
- if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
- const PointerType *SrcPTy = cast<PointerType>(SrcTy);
- const Type *DstElTy = DstPTy->getElementType();
- const Type *SrcElTy = SrcPTy->getElementType();
-
- // If the address spaces don't match, don't eliminate the bitcast, which is
- // required for changing types.
- if (SrcPTy->getAddressSpace() != DstPTy->getAddressSpace())
- return 0;
-
- // If we are casting a alloca to a pointer to a type of the same
- // size, rewrite the allocation instruction to allocate the "right" type.
- // There is no need to modify malloc calls because it is their bitcast that
- // needs to be cleaned up.
- if (AllocaInst *AI = dyn_cast<AllocaInst>(Src))
- if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
- return V;
-
- // If the source and destination are pointers, and this cast is equivalent
- // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
- // This can enhance SROA and other transforms that want type-safe pointers.
- Constant *ZeroUInt = Constant::getNullValue(Type::getInt32Ty(*Context));
- unsigned NumZeros = 0;
- while (SrcElTy != DstElTy &&
- isa<CompositeType>(SrcElTy) && !isa<PointerType>(SrcElTy) &&
- SrcElTy->getNumContainedTypes() /* not "{}" */) {
- SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
- ++NumZeros;
- }
-
- // If we found a path from the src to dest, create the getelementptr now.
- if (SrcElTy == DstElTy) {
- SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
- return GetElementPtrInst::CreateInBounds(Src, Idxs.begin(), Idxs.end(), "",
- ((Instruction*) NULL));
- }
- }
-
- if (const VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
- if (DestVTy->getNumElements() == 1) {
- if (!isa<VectorType>(SrcTy)) {
- Value *Elem = Builder->CreateBitCast(Src, DestVTy->getElementType());
- return InsertElementInst::Create(UndefValue::get(DestTy), Elem,
- Constant::getNullValue(Type::getInt32Ty(*Context)));
- }
- // FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
- }
- }
-
- if (const VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) {
- if (SrcVTy->getNumElements() == 1) {
- if (!isa<VectorType>(DestTy)) {
- Value *Elem =
- Builder->CreateExtractElement(Src,
- Constant::getNullValue(Type::getInt32Ty(*Context)));
- return CastInst::Create(Instruction::BitCast, Elem, DestTy);
- }
- }
- }
-
- if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
- if (SVI->hasOneUse()) {
- // Okay, we have (bitconvert (shuffle ..)). Check to see if this is
- // a bitconvert to a vector with the same # elts.
- if (isa<VectorType>(DestTy) &&
- cast<VectorType>(DestTy)->getNumElements() ==
- SVI->getType()->getNumElements() &&
- SVI->getType()->getNumElements() ==
- cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements()) {
- CastInst *Tmp;
- // If either of the operands is a cast from CI.getType(), then
- // evaluating the shuffle in the casted destination's type will allow
- // us to eliminate at least one cast.
- if (((Tmp = dyn_cast<CastInst>(SVI->getOperand(0))) &&
- Tmp->getOperand(0)->getType() == DestTy) ||
- ((Tmp = dyn_cast<CastInst>(SVI->getOperand(1))) &&
- Tmp->getOperand(0)->getType() == DestTy)) {
- Value *LHS = Builder->CreateBitCast(SVI->getOperand(0), DestTy);
- Value *RHS = Builder->CreateBitCast(SVI->getOperand(1), DestTy);
- // Return a new shuffle vector. Use the same element ID's, as we
- // know the vector types match #elts.
- return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
- }
- }
- }
- }
- return 0;
-}
-
-/// GetSelectFoldableOperands - We want to turn code that looks like this:
-/// %C = or %A, %B
-/// %D = select %cond, %C, %A
-/// into:
-/// %C = select %cond, %B, 0
-/// %D = or %A, %C
-///
-/// Assuming that the specified instruction is an operand to the select, return
-/// a bitmask indicating which operands of this instruction are foldable if they
-/// equal the other incoming value of the select.
-///
-static unsigned GetSelectFoldableOperands(Instruction *I) {
- switch (I->getOpcode()) {
- case Instruction::Add:
- case Instruction::Mul:
- case Instruction::And:
- case Instruction::Or:
- case Instruction::Xor:
- return 3; // Can fold through either operand.
- case Instruction::Sub: // Can only fold on the amount subtracted.
- case Instruction::Shl: // Can only fold on the shift amount.
- case Instruction::LShr:
- case Instruction::AShr:
- return 1;
- default:
- return 0; // Cannot fold
- }
-}
-
-/// GetSelectFoldableConstant - For the same transformation as the previous
-/// function, return the identity constant that goes into the select.
-static Constant *GetSelectFoldableConstant(Instruction *I,
- LLVMContext *Context) {
- switch (I->getOpcode()) {
- default: llvm_unreachable("This cannot happen!");
- case Instruction::Add:
- case Instruction::Sub:
- case Instruction::Or:
- case Instruction::Xor:
- case Instruction::Shl:
- case Instruction::LShr:
- case Instruction::AShr:
- return Constant::getNullValue(I->getType());
- case Instruction::And:
- return Constant::getAllOnesValue(I->getType());
- case Instruction::Mul:
- return ConstantInt::get(I->getType(), 1);
- }
-}
-
-/// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
-/// have the same opcode and only one use each. Try to simplify this.
-Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
- Instruction *FI) {
- if (TI->getNumOperands() == 1) {
- // If this is a non-volatile load or a cast from the same type,
- // merge.
- if (TI->isCast()) {
- if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
- return 0;
- } else {
- return 0; // unknown unary op.
- }
-
- // Fold this by inserting a select from the input values.
- SelectInst *NewSI = SelectInst::Create(SI.getCondition(), TI->getOperand(0),
- FI->getOperand(0), SI.getName()+".v");
- InsertNewInstBefore(NewSI, SI);
- return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
- TI->getType());
- }
-
- // Only handle binary operators here.
- if (!isa<BinaryOperator>(TI))
- return 0;
-
- // Figure out if the operations have any operands in common.
- Value *MatchOp, *OtherOpT, *OtherOpF;
- bool MatchIsOpZero;
- if (TI->getOperand(0) == FI->getOperand(0)) {
- MatchOp = TI->getOperand(0);
- OtherOpT = TI->getOperand(1);
- OtherOpF = FI->getOperand(1);
- MatchIsOpZero = true;
- } else if (TI->getOperand(1) == FI->getOperand(1)) {
- MatchOp = TI->getOperand(1);
- OtherOpT = TI->getOperand(0);
- OtherOpF = FI->getOperand(0);
- MatchIsOpZero = false;
- } else if (!TI->isCommutative()) {
- return 0;
- } else if (TI->getOperand(0) == FI->getOperand(1)) {
- MatchOp = TI->getOperand(0);
- OtherOpT = TI->getOperand(1);
- OtherOpF = FI->getOperand(0);
- MatchIsOpZero = true;
- } else if (TI->getOperand(1) == FI->getOperand(0)) {
- MatchOp = TI->getOperand(1);
- OtherOpT = TI->getOperand(0);
- OtherOpF = FI->getOperand(1);
- MatchIsOpZero = true;
- } else {
- return 0;
- }
-
- // If we reach here, they do have operations in common.
- SelectInst *NewSI = SelectInst::Create(SI.getCondition(), OtherOpT,
- OtherOpF, SI.getName()+".v");
- InsertNewInstBefore(NewSI, SI);
-
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
- if (MatchIsOpZero)
- return BinaryOperator::Create(BO->getOpcode(), MatchOp, NewSI);
- else
- return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp);
- }
- llvm_unreachable("Shouldn't get here");
- return 0;
-}
-
-static bool isSelect01(Constant *C1, Constant *C2) {
- ConstantInt *C1I = dyn_cast<ConstantInt>(C1);
- if (!C1I)
- return false;
- ConstantInt *C2I = dyn_cast<ConstantInt>(C2);
- if (!C2I)
- return false;
- return (C1I->isZero() || C1I->isOne()) && (C2I->isZero() || C2I->isOne());
-}
-
-/// FoldSelectIntoOp - Try fold the select into one of the operands to
-/// facilitate further optimization.
-Instruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal,
- Value *FalseVal) {
- // See the comment above GetSelectFoldableOperands for a description of the
- // transformation we are doing here.
- if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) {
- if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
- !isa<Constant>(FalseVal)) {
- if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
- unsigned OpToFold = 0;
- if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
- OpToFold = 1;
- } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
- OpToFold = 2;
- }
-
- if (OpToFold) {
- Constant *C = GetSelectFoldableConstant(TVI, Context);
- Value *OOp = TVI->getOperand(2-OpToFold);
- // Avoid creating select between 2 constants unless it's selecting
- // between 0 and 1.
- if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
- Instruction *NewSel = SelectInst::Create(SI.getCondition(), OOp, C);
- InsertNewInstBefore(NewSel, SI);
- NewSel->takeName(TVI);
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
- return BinaryOperator::Create(BO->getOpcode(), FalseVal, NewSel);
- llvm_unreachable("Unknown instruction!!");
- }
- }
- }
- }
- }
-
- if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) {
- if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
- !isa<Constant>(TrueVal)) {
- if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
- unsigned OpToFold = 0;
- if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
- OpToFold = 1;
- } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
- OpToFold = 2;
- }
-
- if (OpToFold) {
- Constant *C = GetSelectFoldableConstant(FVI, Context);
- Value *OOp = FVI->getOperand(2-OpToFold);
- // Avoid creating select between 2 constants unless it's selecting
- // between 0 and 1.
- if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
- Instruction *NewSel = SelectInst::Create(SI.getCondition(), C, OOp);
- InsertNewInstBefore(NewSel, SI);
- NewSel->takeName(FVI);
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
- return BinaryOperator::Create(BO->getOpcode(), TrueVal, NewSel);
- llvm_unreachable("Unknown instruction!!");
- }
- }
- }
- }
- }
-
- return 0;
-}
-
-/// visitSelectInstWithICmp - Visit a SelectInst that has an
-/// ICmpInst as its first operand.
-///
-Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI,
- ICmpInst *ICI) {
- bool Changed = false;
- ICmpInst::Predicate Pred = ICI->getPredicate();
- Value *CmpLHS = ICI->getOperand(0);
- Value *CmpRHS = ICI->getOperand(1);
- Value *TrueVal = SI.getTrueValue();
- Value *FalseVal = SI.getFalseValue();
-
- // Check cases where the comparison is with a constant that
- // can be adjusted to fit the min/max idiom. We may edit ICI in
- // place here, so make sure the select is the only user.
- if (ICI->hasOneUse())
- if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) {
- switch (Pred) {
- default: break;
- case ICmpInst::ICMP_ULT:
- case ICmpInst::ICMP_SLT: {
- // X < MIN ? T : F --> F
- if (CI->isMinValue(Pred == ICmpInst::ICMP_SLT))
- return ReplaceInstUsesWith(SI, FalseVal);
- // X < C ? X : C-1 --> X > C-1 ? C-1 : X
- Constant *AdjustedRHS = SubOne(CI);
- if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
- (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
- Pred = ICmpInst::getSwappedPredicate(Pred);
- CmpRHS = AdjustedRHS;
- std::swap(FalseVal, TrueVal);
- ICI->setPredicate(Pred);
- ICI->setOperand(1, CmpRHS);
- SI.setOperand(1, TrueVal);
- SI.setOperand(2, FalseVal);
- Changed = true;
- }
- break;
- }
- case ICmpInst::ICMP_UGT:
- case ICmpInst::ICMP_SGT: {
- // X > MAX ? T : F --> F
- if (CI->isMaxValue(Pred == ICmpInst::ICMP_SGT))
- return ReplaceInstUsesWith(SI, FalseVal);
- // X > C ? X : C+1 --> X < C+1 ? C+1 : X
- Constant *AdjustedRHS = AddOne(CI);
- if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
- (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
- Pred = ICmpInst::getSwappedPredicate(Pred);
- CmpRHS = AdjustedRHS;
- std::swap(FalseVal, TrueVal);
- ICI->setPredicate(Pred);
- ICI->setOperand(1, CmpRHS);
- SI.setOperand(1, TrueVal);
- SI.setOperand(2, FalseVal);
- Changed = true;
- }
- break;
- }
- }
-
- // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed
- // (x >s -1) ? -1 : 0 -> ashr x, 31 -> all ones if not signed
- CmpInst::Predicate Pred = CmpInst::BAD_ICMP_PREDICATE;
- if (match(TrueVal, m_ConstantInt<-1>()) &&
- match(FalseVal, m_ConstantInt<0>()))
- Pred = ICI->getPredicate();
- else if (match(TrueVal, m_ConstantInt<0>()) &&
- match(FalseVal, m_ConstantInt<-1>()))
- Pred = CmpInst::getInversePredicate(ICI->getPredicate());
-
- if (Pred != CmpInst::BAD_ICMP_PREDICATE) {
- // If we are just checking for a icmp eq of a single bit and zext'ing it
- // to an integer, then shift the bit to the appropriate place and then
- // cast to integer to avoid the comparison.
- const APInt &Op1CV = CI->getValue();
-
- // sext (x <s 0) to i32 --> x>>s31 true if signbit set.
- // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear.
- if ((Pred == ICmpInst::ICMP_SLT && Op1CV == 0) ||
- (Pred == ICmpInst::ICMP_SGT && Op1CV.isAllOnesValue())) {
- Value *In = ICI->getOperand(0);
- Value *Sh = ConstantInt::get(In->getType(),
- In->getType()->getScalarSizeInBits()-1);
- In = InsertNewInstBefore(BinaryOperator::CreateAShr(In, Sh,
- In->getName()+".lobit"),
- *ICI);
- if (In->getType() != SI.getType())
- In = CastInst::CreateIntegerCast(In, SI.getType(),
- true/*SExt*/, "tmp", ICI);
-
- if (Pred == ICmpInst::ICMP_SGT)
- In = InsertNewInstBefore(BinaryOperator::CreateNot(In,
- In->getName()+".not"), *ICI);
-
- return ReplaceInstUsesWith(SI, In);
- }
- }
- }
-
- if (CmpLHS == TrueVal && CmpRHS == FalseVal) {
- // Transform (X == Y) ? X : Y -> Y
- if (Pred == ICmpInst::ICMP_EQ)
- return ReplaceInstUsesWith(SI, FalseVal);
- // Transform (X != Y) ? X : Y -> X
- if (Pred == ICmpInst::ICMP_NE)
- return ReplaceInstUsesWith(SI, TrueVal);
- /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
-
- } else if (CmpLHS == FalseVal && CmpRHS == TrueVal) {
- // Transform (X == Y) ? Y : X -> X
- if (Pred == ICmpInst::ICMP_EQ)
- return ReplaceInstUsesWith(SI, FalseVal);
- // Transform (X != Y) ? Y : X -> Y
- if (Pred == ICmpInst::ICMP_NE)
- return ReplaceInstUsesWith(SI, TrueVal);
- /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
- }
- return Changed ? &SI : 0;
-}
-
-
-/// CanSelectOperandBeMappingIntoPredBlock - SI is a select whose condition is a
-/// PHI node (but the two may be in different blocks). See if the true/false
-/// values (V) are live in all of the predecessor blocks of the PHI. For
-/// example, cases like this cannot be mapped:
-///
-/// X = phi [ C1, BB1], [C2, BB2]
-/// Y = add
-/// Z = select X, Y, 0
-///
-/// because Y is not live in BB1/BB2.
-///
-static bool CanSelectOperandBeMappingIntoPredBlock(const Value *V,
- const SelectInst &SI) {
- // If the value is a non-instruction value like a constant or argument, it
- // can always be mapped.
- const Instruction *I = dyn_cast<Instruction>(V);
- if (I == 0) return true;
-
- // If V is a PHI node defined in the same block as the condition PHI, we can
- // map the arguments.
- const PHINode *CondPHI = cast<PHINode>(SI.getCondition());
-
- if (const PHINode *VP = dyn_cast<PHINode>(I))
- if (VP->getParent() == CondPHI->getParent())
- return true;
-
- // Otherwise, if the PHI and select are defined in the same block and if V is
- // defined in a different block, then we can transform it.
- if (SI.getParent() == CondPHI->getParent() &&
- I->getParent() != CondPHI->getParent())
- return true;
-
- // Otherwise we have a 'hard' case and we can't tell without doing more
- // detailed dominator based analysis, punt.
- return false;
-}
-
-/// FoldSPFofSPF - We have an SPF (e.g. a min or max) of an SPF of the form:
-/// SPF2(SPF1(A, B), C)
-Instruction *InstCombiner::FoldSPFofSPF(Instruction *Inner,
- SelectPatternFlavor SPF1,
- Value *A, Value *B,
- Instruction &Outer,
- SelectPatternFlavor SPF2, Value *C) {
- if (C == A || C == B) {
- // MAX(MAX(A, B), B) -> MAX(A, B)
- // MIN(MIN(a, b), a) -> MIN(a, b)
- if (SPF1 == SPF2)
- return ReplaceInstUsesWith(Outer, Inner);
-
- // MAX(MIN(a, b), a) -> a
- // MIN(MAX(a, b), a) -> a
- if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) ||
- (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) ||
- (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) ||
- (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN))
- return ReplaceInstUsesWith(Outer, C);
- }
-
- // TODO: MIN(MIN(A, 23), 97)
- return 0;
-}
-
-
-
-
-Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
- Value *CondVal = SI.getCondition();
- Value *TrueVal = SI.getTrueValue();
- Value *FalseVal = SI.getFalseValue();
-
- // select true, X, Y -> X
- // select false, X, Y -> Y
- if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal))
- return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal);
-
- // select C, X, X -> X
- if (TrueVal == FalseVal)
- return ReplaceInstUsesWith(SI, TrueVal);
-
- if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
- return ReplaceInstUsesWith(SI, FalseVal);
- if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
- return ReplaceInstUsesWith(SI, TrueVal);
- if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
- if (isa<Constant>(TrueVal))
- return ReplaceInstUsesWith(SI, TrueVal);
- else
- return ReplaceInstUsesWith(SI, FalseVal);
- }
-
- if (SI.getType() == Type::getInt1Ty(*Context)) {
- if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) {
- if (C->getZExtValue()) {
- // Change: A = select B, true, C --> A = or B, C
- return BinaryOperator::CreateOr(CondVal, FalseVal);
- } else {
- // Change: A = select B, false, C --> A = and !B, C
- Value *NotCond =
- InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
- "not."+CondVal->getName()), SI);
- return BinaryOperator::CreateAnd(NotCond, FalseVal);
- }
- } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
- if (C->getZExtValue() == false) {
- // Change: A = select B, C, false --> A = and B, C
- return BinaryOperator::CreateAnd(CondVal, TrueVal);
- } else {
- // Change: A = select B, C, true --> A = or !B, C
- Value *NotCond =
- InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
- "not."+CondVal->getName()), SI);
- return BinaryOperator::CreateOr(NotCond, TrueVal);
- }
- }
-
- // select a, b, a -> a&b
- // select a, a, b -> a|b
- if (CondVal == TrueVal)
- return BinaryOperator::CreateOr(CondVal, FalseVal);
- else if (CondVal == FalseVal)
- return BinaryOperator::CreateAnd(CondVal, TrueVal);
- }
-
- // Selecting between two integer constants?
- if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
- if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
- // select C, 1, 0 -> zext C to int
- if (FalseValC->isZero() && TrueValC->getValue() == 1) {
- return CastInst::Create(Instruction::ZExt, CondVal, SI.getType());
- } else if (TrueValC->isZero() && FalseValC->getValue() == 1) {
- // select C, 0, 1 -> zext !C to int
- Value *NotCond =
- InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
- "not."+CondVal->getName()), SI);
- return CastInst::Create(Instruction::ZExt, NotCond, SI.getType());
- }
-
- if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) {
- // If one of the constants is zero (we know they can't both be) and we
- // have an icmp instruction with zero, and we have an 'and' with the
- // non-constant value, eliminate this whole mess. This corresponds to
- // cases like this: ((X & 27) ? 27 : 0)
- if (TrueValC->isZero() || FalseValC->isZero())
- if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
- cast<Constant>(IC->getOperand(1))->isNullValue())
- if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
- if (ICA->getOpcode() == Instruction::And &&
- isa<ConstantInt>(ICA->getOperand(1)) &&
- (ICA->getOperand(1) == TrueValC ||
- ICA->getOperand(1) == FalseValC) &&
- isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
- // Okay, now we know that everything is set up, we just don't
- // know whether we have a icmp_ne or icmp_eq and whether the
- // true or false val is the zero.
- bool ShouldNotVal = !TrueValC->isZero();
- ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
- Value *V = ICA;
- if (ShouldNotVal)
- V = InsertNewInstBefore(BinaryOperator::Create(
- Instruction::Xor, V, ICA->getOperand(1)), SI);
- return ReplaceInstUsesWith(SI, V);
- }
- }
- }
-
- // See if we are selecting two values based on a comparison of the two values.
- if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
- if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
- // Transform (X == Y) ? X : Y -> Y
- if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
- // This is not safe in general for floating point:
- // consider X== -0, Y== +0.
- // It becomes safe if either operand is a nonzero constant.
- ConstantFP *CFPt, *CFPf;
- if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
- !CFPt->getValueAPF().isZero()) ||
- ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
- !CFPf->getValueAPF().isZero()))
- return ReplaceInstUsesWith(SI, FalseVal);
- }
- // Transform (X != Y) ? X : Y -> X
- if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
- return ReplaceInstUsesWith(SI, TrueVal);
- // NOTE: if we wanted to, this is where to detect MIN/MAX
-
- } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
- // Transform (X == Y) ? Y : X -> X
- if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
- // This is not safe in general for floating point:
- // consider X== -0, Y== +0.
- // It becomes safe if either operand is a nonzero constant.
- ConstantFP *CFPt, *CFPf;
- if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
- !CFPt->getValueAPF().isZero()) ||
- ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
- !CFPf->getValueAPF().isZero()))
- return ReplaceInstUsesWith(SI, FalseVal);
- }
- // Transform (X != Y) ? Y : X -> Y
- if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
- return ReplaceInstUsesWith(SI, TrueVal);
- // NOTE: if we wanted to, this is where to detect MIN/MAX
- }
- // NOTE: if we wanted to, this is where to detect ABS
- }
-
- // See if we are selecting two values based on a comparison of the two values.
- if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
- if (Instruction *Result = visitSelectInstWithICmp(SI, ICI))
- return Result;
-
- if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
- if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
- if (TI->hasOneUse() && FI->hasOneUse()) {
- Instruction *AddOp = 0, *SubOp = 0;
-
- // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
- if (TI->getOpcode() == FI->getOpcode())
- if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
- return IV;
-
- // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
- // even legal for FP.
- if ((TI->getOpcode() == Instruction::Sub &&
- FI->getOpcode() == Instruction::Add) ||
- (TI->getOpcode() == Instruction::FSub &&
- FI->getOpcode() == Instruction::FAdd)) {
- AddOp = FI; SubOp = TI;
- } else if ((FI->getOpcode() == Instruction::Sub &&
- TI->getOpcode() == Instruction::Add) ||
- (FI->getOpcode() == Instruction::FSub &&
- TI->getOpcode() == Instruction::FAdd)) {
- AddOp = TI; SubOp = FI;
- }
-
- if (AddOp) {
- Value *OtherAddOp = 0;
- if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
- OtherAddOp = AddOp->getOperand(1);
- } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
- OtherAddOp = AddOp->getOperand(0);
- }
-
- if (OtherAddOp) {
- // So at this point we know we have (Y -> OtherAddOp):
- // select C, (add X, Y), (sub X, Z)
- Value *NegVal; // Compute -Z
- if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
- NegVal = ConstantExpr::getNeg(C);
- } else {
- NegVal = InsertNewInstBefore(
- BinaryOperator::CreateNeg(SubOp->getOperand(1),
- "tmp"), SI);
- }
-
- Value *NewTrueOp = OtherAddOp;
- Value *NewFalseOp = NegVal;
- if (AddOp != TI)
- std::swap(NewTrueOp, NewFalseOp);
- Instruction *NewSel =
- SelectInst::Create(CondVal, NewTrueOp,
- NewFalseOp, SI.getName() + ".p");
-
- NewSel = InsertNewInstBefore(NewSel, SI);
- return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
- }
- }
- }
-
- // See if we can fold the select into one of our operands.
- if (SI.getType()->isInteger()) {
- if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal))
- return FoldI;
-
- // MAX(MAX(a, b), a) -> MAX(a, b)
- // MIN(MIN(a, b), a) -> MIN(a, b)
- // MAX(MIN(a, b), a) -> a
- // MIN(MAX(a, b), a) -> a
- Value *LHS, *RHS, *LHS2, *RHS2;
- if (SelectPatternFlavor SPF = MatchSelectPattern(&SI, LHS, RHS)) {
- if (SelectPatternFlavor SPF2 = MatchSelectPattern(LHS, LHS2, RHS2))
- if (Instruction *R = FoldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2,
- SI, SPF, RHS))
- return R;
- if (SelectPatternFlavor SPF2 = MatchSelectPattern(RHS, LHS2, RHS2))
- if (Instruction *R = FoldSPFofSPF(cast<Instruction>(RHS),SPF2,LHS2,RHS2,
- SI, SPF, LHS))
- return R;
- }
-
- // TODO.
- // ABS(-X) -> ABS(X)
- // ABS(ABS(X)) -> ABS(X)
- }
-
- // See if we can fold the select into a phi node if the condition is a select.
- if (isa<PHINode>(SI.getCondition()))
- // The true/false values have to be live in the PHI predecessor's blocks.
- if (CanSelectOperandBeMappingIntoPredBlock(TrueVal, SI) &&
- CanSelectOperandBeMappingIntoPredBlock(FalseVal, SI))
- if (Instruction *NV = FoldOpIntoPhi(SI))
- return NV;
-
- if (BinaryOperator::isNot(CondVal)) {
- SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
- SI.setOperand(1, FalseVal);
- SI.setOperand(2, TrueVal);
- return &SI;
- }
-
- return 0;
-}
-
-/// EnforceKnownAlignment - If the specified pointer points to an object that
-/// we control, modify the object's alignment to PrefAlign. This isn't
-/// often possible though. If alignment is important, a more reliable approach
-/// is to simply align all global variables and allocation instructions to
-/// their preferred alignment from the beginning.
-///
-static unsigned EnforceKnownAlignment(Value *V,
- unsigned Align, unsigned PrefAlign) {
-
- User *U = dyn_cast<User>(V);
- if (!U) return Align;
-
- switch (Operator::getOpcode(U)) {
- default: break;
- case Instruction::BitCast:
- return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
- case Instruction::GetElementPtr: {
- // If all indexes are zero, it is just the alignment of the base pointer.
- bool AllZeroOperands = true;
- for (User::op_iterator i = U->op_begin() + 1, e = U->op_end(); i != e; ++i)
- if (!isa<Constant>(*i) ||
- !cast<Constant>(*i)->isNullValue()) {
- AllZeroOperands = false;
- break;
- }
-
- if (AllZeroOperands) {
- // Treat this like a bitcast.
- return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
- }
- break;
- }
- }
-
- if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
- // If there is a large requested alignment and we can, bump up the alignment
- // of the global.
- if (!GV->isDeclaration()) {
- if (GV->getAlignment() >= PrefAlign)
- Align = GV->getAlignment();
- else {
- GV->setAlignment(PrefAlign);
- Align = PrefAlign;
- }
- }
- } else if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
- // If there is a requested alignment and if this is an alloca, round up.
- if (AI->getAlignment() >= PrefAlign)
- Align = AI->getAlignment();
- else {
- AI->setAlignment(PrefAlign);
- Align = PrefAlign;
- }
- }
-
- return Align;
-}
-
-/// GetOrEnforceKnownAlignment - If the specified pointer has an alignment that
-/// we can determine, return it, otherwise return 0. If PrefAlign is specified,
-/// and it is more than the alignment of the ultimate object, see if we can
-/// increase the alignment of the ultimate object, making this check succeed.
-unsigned InstCombiner::GetOrEnforceKnownAlignment(Value *V,
- unsigned PrefAlign) {
- unsigned BitWidth = TD ? TD->getTypeSizeInBits(V->getType()) :
- sizeof(PrefAlign) * CHAR_BIT;
- APInt Mask = APInt::getAllOnesValue(BitWidth);
- APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
- ComputeMaskedBits(V, Mask, KnownZero, KnownOne);
- unsigned TrailZ = KnownZero.countTrailingOnes();
- unsigned Align = 1u << std::min(BitWidth - 1, TrailZ);
-
- if (PrefAlign > Align)
- Align = EnforceKnownAlignment(V, Align, PrefAlign);
-
- // We don't need to make any adjustment.
- return Align;
-}
-
-Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
- unsigned DstAlign = GetOrEnforceKnownAlignment(MI->getOperand(1));
- unsigned SrcAlign = GetOrEnforceKnownAlignment(MI->getOperand(2));
- unsigned MinAlign = std::min(DstAlign, SrcAlign);
- unsigned CopyAlign = MI->getAlignment();
-
- if (CopyAlign < MinAlign) {
- MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
- MinAlign, false));
- return MI;
- }
-
- // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
- // load/store.
- ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getOperand(3));
- if (MemOpLength == 0) return 0;
-
- // Source and destination pointer types are always "i8*" for intrinsic. See
- // if the size is something we can handle with a single primitive load/store.
- // A single load+store correctly handles overlapping memory in the memmove
- // case.
- unsigned Size = MemOpLength->getZExtValue();
- if (Size == 0) return MI; // Delete this mem transfer.
-
- if (Size > 8 || (Size&(Size-1)))
- return 0; // If not 1/2/4/8 bytes, exit.
-
- // Use an integer load+store unless we can find something better.
- Type *NewPtrTy =
- PointerType::getUnqual(IntegerType::get(*Context, Size<<3));
-
- // Memcpy forces the use of i8* for the source and destination. That means
- // that if you're using memcpy to move one double around, you'll get a cast
- // from double* to i8*. We'd much rather use a double load+store rather than
- // an i64 load+store, here because this improves the odds that the source or
- // dest address will be promotable. See if we can find a better type than the
- // integer datatype.
- if (Value *Op = getBitCastOperand(MI->getOperand(1))) {
- const Type *SrcETy = cast<PointerType>(Op->getType())->getElementType();
- if (TD && SrcETy->isSized() && TD->getTypeStoreSize(SrcETy) == Size) {
- // The SrcETy might be something like {{{double}}} or [1 x double]. Rip
- // down through these levels if so.
- while (!SrcETy->isSingleValueType()) {
- if (const StructType *STy = dyn_cast<StructType>(SrcETy)) {
- if (STy->getNumElements() == 1)
- SrcETy = STy->getElementType(0);
- else
- break;
- } else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcETy)) {
- if (ATy->getNumElements() == 1)
- SrcETy = ATy->getElementType();
- else
- break;
- } else
- break;
- }
-
- if (SrcETy->isSingleValueType())
- NewPtrTy = PointerType::getUnqual(SrcETy);
- }
- }
-
-
- // If the memcpy/memmove provides better alignment info than we can
- // infer, use it.
- SrcAlign = std::max(SrcAlign, CopyAlign);
- DstAlign = std::max(DstAlign, CopyAlign);
-
- Value *Src = Builder->CreateBitCast(MI->getOperand(2), NewPtrTy);
- Value *Dest = Builder->CreateBitCast(MI->getOperand(1), NewPtrTy);
- Instruction *L = new LoadInst(Src, "tmp", false, SrcAlign);
- InsertNewInstBefore(L, *MI);
- InsertNewInstBefore(new StoreInst(L, Dest, false, DstAlign), *MI);
-
- // Set the size of the copy to 0, it will be deleted on the next iteration.
- MI->setOperand(3, Constant::getNullValue(MemOpLength->getType()));
- return MI;
-}
-
-Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) {
- unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest());
- if (MI->getAlignment() < Alignment) {
- MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
- Alignment, false));
- return MI;
- }
-
- // Extract the length and alignment and fill if they are constant.
- ConstantInt *LenC = dyn_cast<ConstantInt>(MI->getLength());
- ConstantInt *FillC = dyn_cast<ConstantInt>(MI->getValue());
- if (!LenC || !FillC || FillC->getType() != Type::getInt8Ty(*Context))
- return 0;
- uint64_t Len = LenC->getZExtValue();
- Alignment = MI->getAlignment();
-
- // If the length is zero, this is a no-op
- if (Len == 0) return MI; // memset(d,c,0,a) -> noop
-
- // memset(s,c,n) -> store s, c (for n=1,2,4,8)
- if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) {
- const Type *ITy = IntegerType::get(*Context, Len*8); // n=1 -> i8.
-
- Value *Dest = MI->getDest();
- Dest = Builder->CreateBitCast(Dest, PointerType::getUnqual(ITy));
-
- // Alignment 0 is identity for alignment 1 for memset, but not store.
- if (Alignment == 0) Alignment = 1;
-
- // Extract the fill value and store.
- uint64_t Fill = FillC->getZExtValue()*0x0101010101010101ULL;
- InsertNewInstBefore(new StoreInst(ConstantInt::get(ITy, Fill),
- Dest, false, Alignment), *MI);
-
- // Set the size of the copy to 0, it will be deleted on the next iteration.
- MI->setLength(Constant::getNullValue(LenC->getType()));
- return MI;
- }
-
- return 0;
-}
-
-
-/// visitCallInst - CallInst simplification. This mostly only handles folding
-/// of intrinsic instructions. For normal calls, it allows visitCallSite to do
-/// the heavy lifting.
-///
-Instruction *InstCombiner::visitCallInst(CallInst &CI) {
- if (isFreeCall(&CI))
- return visitFree(CI);
-
- // If the caller function is nounwind, mark the call as nounwind, even if the
- // callee isn't.
- if (CI.getParent()->getParent()->doesNotThrow() &&
- !CI.doesNotThrow()) {
- CI.setDoesNotThrow();
- return &CI;
- }
-
- IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
- if (!II) return visitCallSite(&CI);
-
- // Intrinsics cannot occur in an invoke, so handle them here instead of in
- // visitCallSite.
- if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
- bool Changed = false;
-
- // memmove/cpy/set of zero bytes is a noop.
- if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
- if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
-
- if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
- if (CI->getZExtValue() == 1) {
- // Replace the instruction with just byte operations. We would
- // transform other cases to loads/stores, but we don't know if
- // alignment is sufficient.
- }
- }
-
- // If we have a memmove and the source operation is a constant global,
- // then the source and dest pointers can't alias, so we can change this
- // into a call to memcpy.
- if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI)) {
- if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
- if (GVSrc->isConstant()) {
- Module *M = CI.getParent()->getParent()->getParent();
- Intrinsic::ID MemCpyID = Intrinsic::memcpy;
- const Type *Tys[1];
- Tys[0] = CI.getOperand(3)->getType();
- CI.setOperand(0,
- Intrinsic::getDeclaration(M, MemCpyID, Tys, 1));
- Changed = true;
- }
- }
-
- if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
- // memmove(x,x,size) -> noop.
- if (MTI->getSource() == MTI->getDest())
- return EraseInstFromFunction(CI);
- }
-
- // If we can determine a pointer alignment that is bigger than currently
- // set, update the alignment.
- if (isa<MemTransferInst>(MI)) {
- if (Instruction *I = SimplifyMemTransfer(MI))
- return I;
- } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(MI)) {
- if (Instruction *I = SimplifyMemSet(MSI))
- return I;
- }
-
- if (Changed) return II;
- }
-
- switch (II->getIntrinsicID()) {
- default: break;
- case Intrinsic::bswap:
- // bswap(bswap(x)) -> x
- if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(II->getOperand(1)))
- if (Operand->getIntrinsicID() == Intrinsic::bswap)
- return ReplaceInstUsesWith(CI, Operand->getOperand(1));
-
- // bswap(trunc(bswap(x))) -> trunc(lshr(x, c))
- if (TruncInst *TI = dyn_cast<TruncInst>(II->getOperand(1))) {
- if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(TI->getOperand(0)))
- if (Operand->getIntrinsicID() == Intrinsic::bswap) {
- unsigned C = Operand->getType()->getPrimitiveSizeInBits() -
- TI->getType()->getPrimitiveSizeInBits();
- Value *CV = ConstantInt::get(Operand->getType(), C);
- Value *V = Builder->CreateLShr(Operand->getOperand(1), CV);
- return new TruncInst(V, TI->getType());
- }
- }
-
- break;
- case Intrinsic::powi:
- if (ConstantInt *Power = dyn_cast<ConstantInt>(II->getOperand(2))) {
- // powi(x, 0) -> 1.0
- if (Power->isZero())
- return ReplaceInstUsesWith(CI, ConstantFP::get(CI.getType(), 1.0));
- // powi(x, 1) -> x
- if (Power->isOne())
- return ReplaceInstUsesWith(CI, II->getOperand(1));
- // powi(x, -1) -> 1/x
- if (Power->isAllOnesValue())
- return BinaryOperator::CreateFDiv(ConstantFP::get(CI.getType(), 1.0),
- II->getOperand(1));
- }
- break;
-
- case Intrinsic::uadd_with_overflow: {
- Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
- const IntegerType *IT = cast<IntegerType>(II->getOperand(1)->getType());
- uint32_t BitWidth = IT->getBitWidth();
- APInt Mask = APInt::getSignBit(BitWidth);
- APInt LHSKnownZero(BitWidth, 0);
- APInt LHSKnownOne(BitWidth, 0);
- ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
- bool LHSKnownNegative = LHSKnownOne[BitWidth - 1];
- bool LHSKnownPositive = LHSKnownZero[BitWidth - 1];
-
- if (LHSKnownNegative || LHSKnownPositive) {
- APInt RHSKnownZero(BitWidth, 0);
- APInt RHSKnownOne(BitWidth, 0);
- ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
- bool RHSKnownNegative = RHSKnownOne[BitWidth - 1];
- bool RHSKnownPositive = RHSKnownZero[BitWidth - 1];
- if (LHSKnownNegative && RHSKnownNegative) {
- // The sign bit is set in both cases: this MUST overflow.
- // Create a simple add instruction, and insert it into the struct.
- Instruction *Add = BinaryOperator::CreateAdd(LHS, RHS, "", &CI);
- Worklist.Add(Add);
- Constant *V[] = {
- UndefValue::get(LHS->getType()), ConstantInt::getTrue(*Context)
- };
- Constant *Struct = ConstantStruct::get(*Context, V, 2, false);
- return InsertValueInst::Create(Struct, Add, 0);
- }
-
- if (LHSKnownPositive && RHSKnownPositive) {
- // The sign bit is clear in both cases: this CANNOT overflow.
- // Create a simple add instruction, and insert it into the struct.
- Instruction *Add = BinaryOperator::CreateNUWAdd(LHS, RHS, "", &CI);
- Worklist.Add(Add);
- Constant *V[] = {
- UndefValue::get(LHS->getType()), ConstantInt::getFalse(*Context)
- };
- Constant *Struct = ConstantStruct::get(*Context, V, 2, false);
- return InsertValueInst::Create(Struct, Add, 0);
- }
- }
- }
- // FALL THROUGH uadd into sadd
- case Intrinsic::sadd_with_overflow:
- // Canonicalize constants into the RHS.
- if (isa<Constant>(II->getOperand(1)) &&
- !isa<Constant>(II->getOperand(2))) {
- Value *LHS = II->getOperand(1);
- II->setOperand(1, II->getOperand(2));
- II->setOperand(2, LHS);
- return II;
- }
-
- // X + undef -> undef
- if (isa<UndefValue>(II->getOperand(2)))
- return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
-
- if (ConstantInt *RHS = dyn_cast<ConstantInt>(II->getOperand(2))) {
- // X + 0 -> {X, false}
- if (RHS->isZero()) {
- Constant *V[] = {
- UndefValue::get(II->getOperand(0)->getType()),
- ConstantInt::getFalse(*Context)
- };
- Constant *Struct = ConstantStruct::get(*Context, V, 2, false);
- return InsertValueInst::Create(Struct, II->getOperand(1), 0);
- }
- }
- break;
- case Intrinsic::usub_with_overflow:
- case Intrinsic::ssub_with_overflow:
- // undef - X -> undef
- // X - undef -> undef
- if (isa<UndefValue>(II->getOperand(1)) ||
- isa<UndefValue>(II->getOperand(2)))
- return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
-
- if (ConstantInt *RHS = dyn_cast<ConstantInt>(II->getOperand(2))) {
- // X - 0 -> {X, false}
- if (RHS->isZero()) {
- Constant *V[] = {
- UndefValue::get(II->getOperand(1)->getType()),
- ConstantInt::getFalse(*Context)
- };
- Constant *Struct = ConstantStruct::get(*Context, V, 2, false);
- return InsertValueInst::Create(Struct, II->getOperand(1), 0);
- }
- }
- break;
- case Intrinsic::umul_with_overflow:
- case Intrinsic::smul_with_overflow:
- // Canonicalize constants into the RHS.
- if (isa<Constant>(II->getOperand(1)) &&
- !isa<Constant>(II->getOperand(2))) {
- Value *LHS = II->getOperand(1);
- II->setOperand(1, II->getOperand(2));
- II->setOperand(2, LHS);
- return II;
- }
-
- // X * undef -> undef
- if (isa<UndefValue>(II->getOperand(2)))
- return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
-
- if (ConstantInt *RHSI = dyn_cast<ConstantInt>(II->getOperand(2))) {
- // X*0 -> {0, false}
- if (RHSI->isZero())
- return ReplaceInstUsesWith(CI, Constant::getNullValue(II->getType()));
-
- // X * 1 -> {X, false}
- if (RHSI->equalsInt(1)) {
- Constant *V[] = {
- UndefValue::get(II->getOperand(1)->getType()),
- ConstantInt::getFalse(*Context)
- };
- Constant *Struct = ConstantStruct::get(*Context, V, 2, false);
- return InsertValueInst::Create(Struct, II->getOperand(1), 0);
- }
- }
- break;
- case Intrinsic::ppc_altivec_lvx:
- case Intrinsic::ppc_altivec_lvxl:
- case Intrinsic::x86_sse_loadu_ps:
- case Intrinsic::x86_sse2_loadu_pd:
- case Intrinsic::x86_sse2_loadu_dq:
- // Turn PPC lvx -> load if the pointer is known aligned.
- // Turn X86 loadups -> load if the pointer is known aligned.
- if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
- Value *Ptr = Builder->CreateBitCast(II->getOperand(1),
- PointerType::getUnqual(II->getType()));
- return new LoadInst(Ptr);
- }
- break;
- case Intrinsic::ppc_altivec_stvx:
- case Intrinsic::ppc_altivec_stvxl:
- // Turn stvx -> store if the pointer is known aligned.
- if (GetOrEnforceKnownAlignment(II->getOperand(2), 16) >= 16) {
- const Type *OpPtrTy =
- PointerType::getUnqual(II->getOperand(1)->getType());
- Value *Ptr = Builder->CreateBitCast(II->getOperand(2), OpPtrTy);
- return new StoreInst(II->getOperand(1), Ptr);
- }
- break;
- case Intrinsic::x86_sse_storeu_ps:
- case Intrinsic::x86_sse2_storeu_pd:
- case Intrinsic::x86_sse2_storeu_dq:
- // Turn X86 storeu -> store if the pointer is known aligned.
- if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
- const Type *OpPtrTy =
- PointerType::getUnqual(II->getOperand(2)->getType());
- Value *Ptr = Builder->CreateBitCast(II->getOperand(1), OpPtrTy);
- return new StoreInst(II->getOperand(2), Ptr);
- }
- break;
-
- case Intrinsic::x86_sse_cvttss2si: {
- // These intrinsics only demands the 0th element of its input vector. If
- // we can simplify the input based on that, do so now.
- unsigned VWidth =
- cast<VectorType>(II->getOperand(1)->getType())->getNumElements();
- APInt DemandedElts(VWidth, 1);
- APInt UndefElts(VWidth, 0);
- if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
- UndefElts)) {
- II->setOperand(1, V);
- return II;
- }
- break;
- }
-
- case Intrinsic::ppc_altivec_vperm:
- // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
- if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) {
- assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
-
- // Check that all of the elements are integer constants or undefs.
- bool AllEltsOk = true;
- for (unsigned i = 0; i != 16; ++i) {
- if (!isa<ConstantInt>(Mask->getOperand(i)) &&
- !isa<UndefValue>(Mask->getOperand(i))) {
- AllEltsOk = false;
- break;
- }
- }
-
- if (AllEltsOk) {
- // Cast the input vectors to byte vectors.
- Value *Op0 = Builder->CreateBitCast(II->getOperand(1), Mask->getType());
- Value *Op1 = Builder->CreateBitCast(II->getOperand(2), Mask->getType());
- Value *Result = UndefValue::get(Op0->getType());
-
- // Only extract each element once.
- Value *ExtractedElts[32];
- memset(ExtractedElts, 0, sizeof(ExtractedElts));
-
- for (unsigned i = 0; i != 16; ++i) {
- if (isa<UndefValue>(Mask->getOperand(i)))
- continue;
- unsigned Idx=cast<ConstantInt>(Mask->getOperand(i))->getZExtValue();
- Idx &= 31; // Match the hardware behavior.
-
- if (ExtractedElts[Idx] == 0) {
- ExtractedElts[Idx] =
- Builder->CreateExtractElement(Idx < 16 ? Op0 : Op1,
- ConstantInt::get(Type::getInt32Ty(*Context), Idx&15, false),
- "tmp");
- }
-
- // Insert this value into the result vector.
- Result = Builder->CreateInsertElement(Result, ExtractedElts[Idx],
- ConstantInt::get(Type::getInt32Ty(*Context), i, false),
- "tmp");
- }
- return CastInst::Create(Instruction::BitCast, Result, CI.getType());
- }
- }
- break;
-
- case Intrinsic::stackrestore: {
- // If the save is right next to the restore, remove the restore. This can
- // happen when variable allocas are DCE'd.
- if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
- if (SS->getIntrinsicID() == Intrinsic::stacksave) {
- BasicBlock::iterator BI = SS;
- if (&*++BI == II)
- return EraseInstFromFunction(CI);
- }
- }
-
- // Scan down this block to see if there is another stack restore in the
- // same block without an intervening call/alloca.
- BasicBlock::iterator BI = II;
- TerminatorInst *TI = II->getParent()->getTerminator();
- bool CannotRemove = false;
- for (++BI; &*BI != TI; ++BI) {
- if (isa<AllocaInst>(BI) || isMalloc(BI)) {
- CannotRemove = true;
- break;
- }
- if (CallInst *BCI = dyn_cast<CallInst>(BI)) {
- if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BCI)) {
- // If there is a stackrestore below this one, remove this one.
- if (II->getIntrinsicID() == Intrinsic::stackrestore)
- return EraseInstFromFunction(CI);
- // Otherwise, ignore the intrinsic.
- } else {
- // If we found a non-intrinsic call, we can't remove the stack
- // restore.
- CannotRemove = true;
- break;
- }
- }
- }
-
- // If the stack restore is in a return/unwind block and if there are no
- // allocas or calls between the restore and the return, nuke the restore.
- if (!CannotRemove && (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)))
- return EraseInstFromFunction(CI);
- break;
- }
- }
-
- return visitCallSite(II);
-}
-
-// InvokeInst simplification
-//
-Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
- return visitCallSite(&II);
-}
-
-/// isSafeToEliminateVarargsCast - If this cast does not affect the value
-/// passed through the varargs area, we can eliminate the use of the cast.
-static bool isSafeToEliminateVarargsCast(const CallSite CS,
- const CastInst * const CI,
- const TargetData * const TD,
- const int ix) {
- if (!CI->isLosslessCast())
- return false;
-
- // The size of ByVal arguments is derived from the type, so we
- // can't change to a type with a different size. If the size were
- // passed explicitly we could avoid this check.
- if (!CS.paramHasAttr(ix, Attribute::ByVal))
- return true;
-
- const Type* SrcTy =
- cast<PointerType>(CI->getOperand(0)->getType())->getElementType();
- const Type* DstTy = cast<PointerType>(CI->getType())->getElementType();
- if (!SrcTy->isSized() || !DstTy->isSized())
- return false;
- if (!TD || TD->getTypeAllocSize(SrcTy) != TD->getTypeAllocSize(DstTy))
- return false;
- return true;
-}
-
-// visitCallSite - Improvements for call and invoke instructions.
-//
-Instruction *InstCombiner::visitCallSite(CallSite CS) {
- bool Changed = false;
-
- // If the callee is a constexpr cast of a function, attempt to move the cast
- // to the arguments of the call/invoke.
- if (transformConstExprCastCall(CS)) return 0;
-
- Value *Callee = CS.getCalledValue();
-
- if (Function *CalleeF = dyn_cast<Function>(Callee))
- if (CalleeF->getCallingConv() != CS.getCallingConv()) {
- Instruction *OldCall = CS.getInstruction();
- // If the call and callee calling conventions don't match, this call must
- // be unreachable, as the call is undefined.
- new StoreInst(ConstantInt::getTrue(*Context),
- UndefValue::get(Type::getInt1PtrTy(*Context)),
- OldCall);
- // If OldCall dues not return void then replaceAllUsesWith undef.
- // This allows ValueHandlers and custom metadata to adjust itself.
- if (!OldCall->getType()->isVoidTy())
- OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
- if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
- return EraseInstFromFunction(*OldCall);
- return 0;
- }
-
- if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
- // This instruction is not reachable, just remove it. We insert a store to
- // undef so that we know that this code is not reachable, despite the fact
- // that we can't modify the CFG here.
- new StoreInst(ConstantInt::getTrue(*Context),
- UndefValue::get(Type::getInt1PtrTy(*Context)),
- CS.getInstruction());
-
- // If CS dues not return void then replaceAllUsesWith undef.
- // This allows ValueHandlers and custom metadata to adjust itself.
- if (!CS.getInstruction()->getType()->isVoidTy())
- CS.getInstruction()->
- replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
-
- if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
- // Don't break the CFG, insert a dummy cond branch.
- BranchInst::Create(II->getNormalDest(), II->getUnwindDest(),
- ConstantInt::getTrue(*Context), II);
- }
- return EraseInstFromFunction(*CS.getInstruction());
- }
-
- if (BitCastInst *BC = dyn_cast<BitCastInst>(Callee))
- if (IntrinsicInst *In = dyn_cast<IntrinsicInst>(BC->getOperand(0)))
- if (In->getIntrinsicID() == Intrinsic::init_trampoline)
- return transformCallThroughTrampoline(CS);
-
- const PointerType *PTy = cast<PointerType>(Callee->getType());
- const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
- if (FTy->isVarArg()) {
- int ix = FTy->getNumParams() + (isa<InvokeInst>(Callee) ? 3 : 1);
- // See if we can optimize any arguments passed through the varargs area of
- // the call.
- for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
- E = CS.arg_end(); I != E; ++I, ++ix) {
- CastInst *CI = dyn_cast<CastInst>(*I);
- if (CI && isSafeToEliminateVarargsCast(CS, CI, TD, ix)) {
- *I = CI->getOperand(0);
- Changed = true;
- }
- }
- }
-
- if (isa<InlineAsm>(Callee) && !CS.doesNotThrow()) {
- // Inline asm calls cannot throw - mark them 'nounwind'.
- CS.setDoesNotThrow();
- Changed = true;
- }
-
- return Changed ? CS.getInstruction() : 0;
-}
-
-// transformConstExprCastCall - If the callee is a constexpr cast of a function,
-// attempt to move the cast to the arguments of the call/invoke.
-//
-bool InstCombiner::transformConstExprCastCall(CallSite CS) {
- if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
- ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
- if (CE->getOpcode() != Instruction::BitCast ||
- !isa<Function>(CE->getOperand(0)))
- return false;
- Function *Callee = cast<Function>(CE->getOperand(0));
- Instruction *Caller = CS.getInstruction();
- const AttrListPtr &CallerPAL = CS.getAttributes();
-
- // Okay, this is a cast from a function to a different type. Unless doing so
- // would cause a type conversion of one of our arguments, change this call to
- // be a direct call with arguments casted to the appropriate types.
- //
- const FunctionType *FT = Callee->getFunctionType();
- const Type *OldRetTy = Caller->getType();
- const Type *NewRetTy = FT->getReturnType();
-
- if (isa<StructType>(NewRetTy))
- return false; // TODO: Handle multiple return values.
-
- // Check to see if we are changing the return type...
- if (OldRetTy != NewRetTy) {
- if (Callee->isDeclaration() &&
- // Conversion is ok if changing from one pointer type to another or from
- // a pointer to an integer of the same size.
- !((isa<PointerType>(OldRetTy) || !TD ||
- OldRetTy == TD->getIntPtrType(Caller->getContext())) &&
- (isa<PointerType>(NewRetTy) || !TD ||
- NewRetTy == TD->getIntPtrType(Caller->getContext()))))
- return false; // Cannot transform this return value.
-
- if (!Caller->use_empty() &&
- // void -> non-void is handled specially
- !NewRetTy->isVoidTy() && !CastInst::isCastable(NewRetTy, OldRetTy))
- return false; // Cannot transform this return value.
-
- if (!CallerPAL.isEmpty() && !Caller->use_empty()) {
- Attributes RAttrs = CallerPAL.getRetAttributes();
- if (RAttrs & Attribute::typeIncompatible(NewRetTy))
- return false; // Attribute not compatible with transformed value.
- }
-
- // If the callsite is an invoke instruction, and the return value is used by
- // a PHI node in a successor, we cannot change the return type of the call
- // because there is no place to put the cast instruction (without breaking
- // the critical edge). Bail out in this case.
- if (!Caller->use_empty())
- if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
- for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
- UI != E; ++UI)
- if (PHINode *PN = dyn_cast<PHINode>(*UI))
- if (PN->getParent() == II->getNormalDest() ||
- PN->getParent() == II->getUnwindDest())
- return false;
- }
-
- unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
- unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
-
- CallSite::arg_iterator AI = CS.arg_begin();
- for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
- const Type *ParamTy = FT->getParamType(i);
- const Type *ActTy = (*AI)->getType();
-
- if (!CastInst::isCastable(ActTy, ParamTy))
- return false; // Cannot transform this parameter value.
-
- if (CallerPAL.getParamAttributes(i + 1)
- & Attribute::typeIncompatible(ParamTy))
- return false; // Attribute not compatible with transformed value.
-
- // Converting from one pointer type to another or between a pointer and an
- // integer of the same size is safe even if we do not have a body.
- bool isConvertible = ActTy == ParamTy ||
- (TD && ((isa<PointerType>(ParamTy) ||
- ParamTy == TD->getIntPtrType(Caller->getContext())) &&
- (isa<PointerType>(ActTy) ||
- ActTy == TD->getIntPtrType(Caller->getContext()))));
- if (Callee->isDeclaration() && !isConvertible) return false;
- }
-
- if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
- Callee->isDeclaration())
- return false; // Do not delete arguments unless we have a function body.
-
- if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
- !CallerPAL.isEmpty())
- // In this case we have more arguments than the new function type, but we
- // won't be dropping them. Check that these extra arguments have attributes
- // that are compatible with being a vararg call argument.
- for (unsigned i = CallerPAL.getNumSlots(); i; --i) {
- if (CallerPAL.getSlot(i - 1).Index <= FT->getNumParams())
- break;
- Attributes PAttrs = CallerPAL.getSlot(i - 1).Attrs;
- if (PAttrs & Attribute::VarArgsIncompatible)
- return false;
- }
-
- // Okay, we decided that this is a safe thing to do: go ahead and start
- // inserting cast instructions as necessary...
- std::vector<Value*> Args;
- Args.reserve(NumActualArgs);
- SmallVector<AttributeWithIndex, 8> attrVec;
- attrVec.reserve(NumCommonArgs);
-
- // Get any return attributes.
- Attributes RAttrs = CallerPAL.getRetAttributes();
-
- // If the return value is not being used, the type may not be compatible
- // with the existing attributes. Wipe out any problematic attributes.
- RAttrs &= ~Attribute::typeIncompatible(NewRetTy);
-
- // Add the new return attributes.
- if (RAttrs)
- attrVec.push_back(AttributeWithIndex::get(0, RAttrs));
-
- AI = CS.arg_begin();
- for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
- const Type *ParamTy = FT->getParamType(i);
- if ((*AI)->getType() == ParamTy) {
- Args.push_back(*AI);
- } else {
- Instruction::CastOps opcode = CastInst::getCastOpcode(*AI,
- false, ParamTy, false);
- Args.push_back(Builder->CreateCast(opcode, *AI, ParamTy, "tmp"));
- }
-
- // Add any parameter attributes.
- if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
- attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
- }
-
- // If the function takes more arguments than the call was taking, add them
- // now.
- for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
- Args.push_back(Constant::getNullValue(FT->getParamType(i)));
-
- // If we are removing arguments to the function, emit an obnoxious warning.
- if (FT->getNumParams() < NumActualArgs) {
- if (!FT->isVarArg()) {
- errs() << "WARNING: While resolving call to function '"
- << Callee->getName() << "' arguments were dropped!\n";
- } else {
- // Add all of the arguments in their promoted form to the arg list.
- for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
- const Type *PTy = getPromotedType((*AI)->getType());
- if (PTy != (*AI)->getType()) {
- // Must promote to pass through va_arg area!
- Instruction::CastOps opcode =
- CastInst::getCastOpcode(*AI, false, PTy, false);
- Args.push_back(Builder->CreateCast(opcode, *AI, PTy, "tmp"));
- } else {
- Args.push_back(*AI);
- }
-
- // Add any parameter attributes.
- if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
- attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
- }
- }
- }
-
- if (Attributes FnAttrs = CallerPAL.getFnAttributes())
- attrVec.push_back(AttributeWithIndex::get(~0, FnAttrs));
-
- if (NewRetTy->isVoidTy())
- Caller->setName(""); // Void type should not have a name.
-
- const AttrListPtr &NewCallerPAL = AttrListPtr::get(attrVec.begin(),
- attrVec.end());
-
- Instruction *NC;
- if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
- NC = InvokeInst::Create(Callee, II->getNormalDest(), II->getUnwindDest(),
- Args.begin(), Args.end(),
- Caller->getName(), Caller);
- cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
- cast<InvokeInst>(NC)->setAttributes(NewCallerPAL);
- } else {
- NC = CallInst::Create(Callee, Args.begin(), Args.end(),
- Caller->getName(), Caller);
- CallInst *CI = cast<CallInst>(Caller);
- if (CI->isTailCall())
- cast<CallInst>(NC)->setTailCall();
- cast<CallInst>(NC)->setCallingConv(CI->getCallingConv());
- cast<CallInst>(NC)->setAttributes(NewCallerPAL);
- }
-
- // Insert a cast of the return type as necessary.
- Value *NV = NC;
- if (OldRetTy != NV->getType() && !Caller->use_empty()) {
- if (!NV->getType()->isVoidTy()) {
- Instruction::CastOps opcode = CastInst::getCastOpcode(NC, false,
- OldRetTy, false);
- NV = NC = CastInst::Create(opcode, NC, OldRetTy, "tmp");
-
- // If this is an invoke instruction, we should insert it after the first
- // non-phi, instruction in the normal successor block.
- if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
- BasicBlock::iterator I = II->getNormalDest()->getFirstNonPHI();
- InsertNewInstBefore(NC, *I);
- } else {
- // Otherwise, it's a call, just insert cast right after the call instr
- InsertNewInstBefore(NC, *Caller);
- }
- Worklist.AddUsersToWorkList(*Caller);
- } else {
- NV = UndefValue::get(Caller->getType());
- }
- }
-
-
- if (!Caller->use_empty())
- Caller->replaceAllUsesWith(NV);
-
- EraseInstFromFunction(*Caller);
- return true;
-}
-
-// transformCallThroughTrampoline - Turn a call to a function created by the
-// init_trampoline intrinsic into a direct call to the underlying function.
-//
-Instruction *InstCombiner::transformCallThroughTrampoline(CallSite CS) {
- Value *Callee = CS.getCalledValue();
- const PointerType *PTy = cast<PointerType>(Callee->getType());
- const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
- const AttrListPtr &Attrs = CS.getAttributes();
-
- // If the call already has the 'nest' attribute somewhere then give up -
- // otherwise 'nest' would occur twice after splicing in the chain.
- if (Attrs.hasAttrSomewhere(Attribute::Nest))
- return 0;
-
- IntrinsicInst *Tramp =
- cast<IntrinsicInst>(cast<BitCastInst>(Callee)->getOperand(0));
-
- Function *NestF = cast<Function>(Tramp->getOperand(2)->stripPointerCasts());
- const PointerType *NestFPTy = cast<PointerType>(NestF->getType());
- const FunctionType *NestFTy = cast<FunctionType>(NestFPTy->getElementType());
-
- const AttrListPtr &NestAttrs = NestF->getAttributes();
- if (!NestAttrs.isEmpty()) {
- unsigned NestIdx = 1;
- const Type *NestTy = 0;
- Attributes NestAttr = Attribute::None;
-
- // Look for a parameter marked with the 'nest' attribute.
- for (FunctionType::param_iterator I = NestFTy->param_begin(),
- E = NestFTy->param_end(); I != E; ++NestIdx, ++I)
- if (NestAttrs.paramHasAttr(NestIdx, Attribute::Nest)) {
- // Record the parameter type and any other attributes.
- NestTy = *I;
- NestAttr = NestAttrs.getParamAttributes(NestIdx);
- break;
- }
-
- if (NestTy) {
- Instruction *Caller = CS.getInstruction();
- std::vector<Value*> NewArgs;
- NewArgs.reserve(unsigned(CS.arg_end()-CS.arg_begin())+1);
-
- SmallVector<AttributeWithIndex, 8> NewAttrs;
- NewAttrs.reserve(Attrs.getNumSlots() + 1);
-
- // Insert the nest argument into the call argument list, which may
- // mean appending it. Likewise for attributes.
-
- // Add any result attributes.
- if (Attributes Attr = Attrs.getRetAttributes())
- NewAttrs.push_back(AttributeWithIndex::get(0, Attr));
-
- {
- unsigned Idx = 1;
- CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
- do {
- if (Idx == NestIdx) {
- // Add the chain argument and attributes.
- Value *NestVal = Tramp->getOperand(3);
- if (NestVal->getType() != NestTy)
- NestVal = new BitCastInst(NestVal, NestTy, "nest", Caller);
- NewArgs.push_back(NestVal);
- NewAttrs.push_back(AttributeWithIndex::get(NestIdx, NestAttr));
- }
-
- if (I == E)
- break;
-
- // Add the original argument and attributes.
- NewArgs.push_back(*I);
- if (Attributes Attr = Attrs.getParamAttributes(Idx))
- NewAttrs.push_back
- (AttributeWithIndex::get(Idx + (Idx >= NestIdx), Attr));
-
- ++Idx, ++I;
- } while (1);
- }
-
- // Add any function attributes.
- if (Attributes Attr = Attrs.getFnAttributes())
- NewAttrs.push_back(AttributeWithIndex::get(~0, Attr));
-
- // The trampoline may have been bitcast to a bogus type (FTy).
- // Handle this by synthesizing a new function type, equal to FTy
- // with the chain parameter inserted.
-
- std::vector<const Type*> NewTypes;
- NewTypes.reserve(FTy->getNumParams()+1);
-
- // Insert the chain's type into the list of parameter types, which may
- // mean appending it.
- {
- unsigned Idx = 1;
- FunctionType::param_iterator I = FTy->param_begin(),
- E = FTy->param_end();
-
- do {
- if (Idx == NestIdx)
- // Add the chain's type.
- NewTypes.push_back(NestTy);
-
- if (I == E)
- break;
-
- // Add the original type.
- NewTypes.push_back(*I);
-
- ++Idx, ++I;
- } while (1);
- }
-
- // Replace the trampoline call with a direct call. Let the generic
- // code sort out any function type mismatches.
- FunctionType *NewFTy = FunctionType::get(FTy->getReturnType(), NewTypes,
- FTy->isVarArg());
- Constant *NewCallee =
- NestF->getType() == PointerType::getUnqual(NewFTy) ?
- NestF : ConstantExpr::getBitCast(NestF,
- PointerType::getUnqual(NewFTy));
- const AttrListPtr &NewPAL = AttrListPtr::get(NewAttrs.begin(),
- NewAttrs.end());
-
- Instruction *NewCaller;
- if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
- NewCaller = InvokeInst::Create(NewCallee,
- II->getNormalDest(), II->getUnwindDest(),
- NewArgs.begin(), NewArgs.end(),
- Caller->getName(), Caller);
- cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
- cast<InvokeInst>(NewCaller)->setAttributes(NewPAL);
- } else {
- NewCaller = CallInst::Create(NewCallee, NewArgs.begin(), NewArgs.end(),
- Caller->getName(), Caller);
- if (cast<CallInst>(Caller)->isTailCall())
- cast<CallInst>(NewCaller)->setTailCall();
- cast<CallInst>(NewCaller)->
- setCallingConv(cast<CallInst>(Caller)->getCallingConv());
- cast<CallInst>(NewCaller)->setAttributes(NewPAL);
- }
- if (!Caller->getType()->isVoidTy())
- Caller->replaceAllUsesWith(NewCaller);
- Caller->eraseFromParent();
- Worklist.Remove(Caller);
- return 0;
- }
- }
-
- // Replace the trampoline call with a direct call. Since there is no 'nest'
- // parameter, there is no need to adjust the argument list. Let the generic
- // code sort out any function type mismatches.
- Constant *NewCallee =
- NestF->getType() == PTy ? NestF :
- ConstantExpr::getBitCast(NestF, PTy);
- CS.setCalledFunction(NewCallee);
- return CS.getInstruction();
-}
-
-/// FoldPHIArgBinOpIntoPHI - If we have something like phi [add (a,b), add(a,c)]
-/// and if a/b/c and the add's all have a single use, turn this into a phi
-/// and a single binop.
-Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
- Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
- assert(isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst));
- unsigned Opc = FirstInst->getOpcode();
- Value *LHSVal = FirstInst->getOperand(0);
- Value *RHSVal = FirstInst->getOperand(1);
-
- const Type *LHSType = LHSVal->getType();
- const Type *RHSType = RHSVal->getType();
-
- // Scan to see if all operands are the same opcode, and all have one use.
- for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
- Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
- if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
- // Verify type of the LHS matches so we don't fold cmp's of different
- // types or GEP's with different index types.
- I->getOperand(0)->getType() != LHSType ||
- I->getOperand(1)->getType() != RHSType)
- return 0;
-
- // If they are CmpInst instructions, check their predicates
- if (Opc == Instruction::ICmp || Opc == Instruction::FCmp)
- if (cast<CmpInst>(I)->getPredicate() !=
- cast<CmpInst>(FirstInst)->getPredicate())
- return 0;
-
- // Keep track of which operand needs a phi node.
- if (I->getOperand(0) != LHSVal) LHSVal = 0;
- if (I->getOperand(1) != RHSVal) RHSVal = 0;
- }
-
- // If both LHS and RHS would need a PHI, don't do this transformation,
- // because it would increase the number of PHIs entering the block,
- // which leads to higher register pressure. This is especially
- // bad when the PHIs are in the header of a loop.
- if (!LHSVal && !RHSVal)
- return 0;
-
- // Otherwise, this is safe to transform!
-
- Value *InLHS = FirstInst->getOperand(0);
- Value *InRHS = FirstInst->getOperand(1);
- PHINode *NewLHS = 0, *NewRHS = 0;
- if (LHSVal == 0) {
- NewLHS = PHINode::Create(LHSType,
- FirstInst->getOperand(0)->getName() + ".pn");
- NewLHS->reserveOperandSpace(PN.getNumOperands()/2);
- NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0));
- InsertNewInstBefore(NewLHS, PN);
- LHSVal = NewLHS;
- }
-
- if (RHSVal == 0) {
- NewRHS = PHINode::Create(RHSType,
- FirstInst->getOperand(1)->getName() + ".pn");
- NewRHS->reserveOperandSpace(PN.getNumOperands()/2);
- NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0));
- InsertNewInstBefore(NewRHS, PN);
- RHSVal = NewRHS;
- }
-
- // Add all operands to the new PHIs.
- if (NewLHS || NewRHS) {
- for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
- Instruction *InInst = cast<Instruction>(PN.getIncomingValue(i));
- if (NewLHS) {
- Value *NewInLHS = InInst->getOperand(0);
- NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i));
- }
- if (NewRHS) {
- Value *NewInRHS = InInst->getOperand(1);
- NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i));
- }
- }
- }
-
- if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
- return BinaryOperator::Create(BinOp->getOpcode(), LHSVal, RHSVal);
- CmpInst *CIOp = cast<CmpInst>(FirstInst);
- return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
- LHSVal, RHSVal);
-}
-
-Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
- GetElementPtrInst *FirstInst =cast<GetElementPtrInst>(PN.getIncomingValue(0));
-
- SmallVector<Value*, 16> FixedOperands(FirstInst->op_begin(),
- FirstInst->op_end());
- // This is true if all GEP bases are allocas and if all indices into them are
- // constants.
- bool AllBasePointersAreAllocas = true;
-
- // We don't want to replace this phi if the replacement would require
- // more than one phi, which leads to higher register pressure. This is
- // especially bad when the PHIs are in the header of a loop.
- bool NeededPhi = false;
-
- // Scan to see if all operands are the same opcode, and all have one use.
- for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
- GetElementPtrInst *GEP= dyn_cast<GetElementPtrInst>(PN.getIncomingValue(i));
- if (!GEP || !GEP->hasOneUse() || GEP->getType() != FirstInst->getType() ||
- GEP->getNumOperands() != FirstInst->getNumOperands())
- return 0;
-
- // Keep track of whether or not all GEPs are of alloca pointers.
- if (AllBasePointersAreAllocas &&
- (!isa<AllocaInst>(GEP->getOperand(0)) ||
- !GEP->hasAllConstantIndices()))
- AllBasePointersAreAllocas = false;
-
- // Compare the operand lists.
- for (unsigned op = 0, e = FirstInst->getNumOperands(); op != e; ++op) {
- if (FirstInst->getOperand(op) == GEP->getOperand(op))
- continue;
-
- // Don't merge two GEPs when two operands differ (introducing phi nodes)
- // if one of the PHIs has a constant for the index. The index may be
- // substantially cheaper to compute for the constants, so making it a
- // variable index could pessimize the path. This also handles the case
- // for struct indices, which must always be constant.
- if (isa<ConstantInt>(FirstInst->getOperand(op)) ||
- isa<ConstantInt>(GEP->getOperand(op)))
- return 0;
-
- if (FirstInst->getOperand(op)->getType() !=GEP->getOperand(op)->getType())
- return 0;
-
- // If we already needed a PHI for an earlier operand, and another operand
- // also requires a PHI, we'd be introducing more PHIs than we're
- // eliminating, which increases register pressure on entry to the PHI's
- // block.
- if (NeededPhi)
- return 0;
-
- FixedOperands[op] = 0; // Needs a PHI.
- NeededPhi = true;
- }
- }
-
- // If all of the base pointers of the PHI'd GEPs are from allocas, don't
- // bother doing this transformation. At best, this will just save a bit of
- // offset calculation, but all the predecessors will have to materialize the
- // stack address into a register anyway. We'd actually rather *clone* the
- // load up into the predecessors so that we have a load of a gep of an alloca,
- // which can usually all be folded into the load.
- if (AllBasePointersAreAllocas)
- return 0;
-
- // Otherwise, this is safe to transform. Insert PHI nodes for each operand
- // that is variable.
- SmallVector<PHINode*, 16> OperandPhis(FixedOperands.size());
-
- bool HasAnyPHIs = false;
- for (unsigned i = 0, e = FixedOperands.size(); i != e; ++i) {
- if (FixedOperands[i]) continue; // operand doesn't need a phi.
- Value *FirstOp = FirstInst->getOperand(i);
- PHINode *NewPN = PHINode::Create(FirstOp->getType(),
- FirstOp->getName()+".pn");
- InsertNewInstBefore(NewPN, PN);
-
- NewPN->reserveOperandSpace(e);
- NewPN->addIncoming(FirstOp, PN.getIncomingBlock(0));
- OperandPhis[i] = NewPN;
- FixedOperands[i] = NewPN;
- HasAnyPHIs = true;
- }
-
-
- // Add all operands to the new PHIs.
- if (HasAnyPHIs) {
- for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
- GetElementPtrInst *InGEP =cast<GetElementPtrInst>(PN.getIncomingValue(i));
- BasicBlock *InBB = PN.getIncomingBlock(i);
-
- for (unsigned op = 0, e = OperandPhis.size(); op != e; ++op)
- if (PHINode *OpPhi = OperandPhis[op])
- OpPhi->addIncoming(InGEP->getOperand(op), InBB);
- }
- }
-
- Value *Base = FixedOperands[0];
- return cast<GEPOperator>(FirstInst)->isInBounds() ?
- GetElementPtrInst::CreateInBounds(Base, FixedOperands.begin()+1,
- FixedOperands.end()) :
- GetElementPtrInst::Create(Base, FixedOperands.begin()+1,
- FixedOperands.end());
-}
-
-
-/// isSafeAndProfitableToSinkLoad - Return true if we know that it is safe to
-/// sink the load out of the block that defines it. This means that it must be
-/// obvious the value of the load is not changed from the point of the load to
-/// the end of the block it is in.
-///
-/// Finally, it is safe, but not profitable, to sink a load targetting a
-/// non-address-taken alloca. Doing so will cause us to not promote the alloca
-/// to a register.
-static bool isSafeAndProfitableToSinkLoad(LoadInst *L) {
- BasicBlock::iterator BBI = L, E = L->getParent()->end();
-
- for (++BBI; BBI != E; ++BBI)
- if (BBI->mayWriteToMemory())
- return false;
-
- // Check for non-address taken alloca. If not address-taken already, it isn't
- // profitable to do this xform.
- if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) {
- bool isAddressTaken = false;
- for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
- UI != E; ++UI) {
- if (isa<LoadInst>(UI)) continue;
- if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
- // If storing TO the alloca, then the address isn't taken.
- if (SI->getOperand(1) == AI) continue;
- }
- isAddressTaken = true;
- break;
- }
-
- if (!isAddressTaken && AI->isStaticAlloca())
- return false;
- }
-
- // If this load is a load from a GEP with a constant offset from an alloca,
- // then we don't want to sink it. In its present form, it will be
- // load [constant stack offset]. Sinking it will cause us to have to
- // materialize the stack addresses in each predecessor in a register only to
- // do a shared load from register in the successor.
- if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(L->getOperand(0)))
- if (AllocaInst *AI = dyn_cast<AllocaInst>(GEP->getOperand(0)))
- if (AI->isStaticAlloca() && GEP->hasAllConstantIndices())
- return false;
-
- return true;
-}
-
-Instruction *InstCombiner::FoldPHIArgLoadIntoPHI(PHINode &PN) {
- LoadInst *FirstLI = cast<LoadInst>(PN.getIncomingValue(0));
-
- // When processing loads, we need to propagate two bits of information to the
- // sunk load: whether it is volatile, and what its alignment is. We currently
- // don't sink loads when some have their alignment specified and some don't.
- // visitLoadInst will propagate an alignment onto the load when TD is around,
- // and if TD isn't around, we can't handle the mixed case.
- bool isVolatile = FirstLI->isVolatile();
- unsigned LoadAlignment = FirstLI->getAlignment();
-
- // We can't sink the load if the loaded value could be modified between the
- // load and the PHI.
- if (FirstLI->getParent() != PN.getIncomingBlock(0) ||
- !isSafeAndProfitableToSinkLoad(FirstLI))
- return 0;
-
- // If the PHI is of volatile loads and the load block has multiple
- // successors, sinking it would remove a load of the volatile value from
- // the path through the other successor.
- if (isVolatile &&
- FirstLI->getParent()->getTerminator()->getNumSuccessors() != 1)
- return 0;
-
- // Check to see if all arguments are the same operation.
- for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
- LoadInst *LI = dyn_cast<LoadInst>(PN.getIncomingValue(i));
- if (!LI || !LI->hasOneUse())
- return 0;
-
- // We can't sink the load if the loaded value could be modified between
- // the load and the PHI.
- if (LI->isVolatile() != isVolatile ||
- LI->getParent() != PN.getIncomingBlock(i) ||
- !isSafeAndProfitableToSinkLoad(LI))
- return 0;
-
- // If some of the loads have an alignment specified but not all of them,
- // we can't do the transformation.
- if ((LoadAlignment != 0) != (LI->getAlignment() != 0))
- return 0;
-
- LoadAlignment = std::min(LoadAlignment, LI->getAlignment());
-
- // If the PHI is of volatile loads and the load block has multiple
- // successors, sinking it would remove a load of the volatile value from
- // the path through the other successor.
- if (isVolatile &&
- LI->getParent()->getTerminator()->getNumSuccessors() != 1)
- return 0;
- }
-
- // Okay, they are all the same operation. Create a new PHI node of the
- // correct type, and PHI together all of the LHS's of the instructions.
- PHINode *NewPN = PHINode::Create(FirstLI->getOperand(0)->getType(),
- PN.getName()+".in");
- NewPN->reserveOperandSpace(PN.getNumOperands()/2);
-
- Value *InVal = FirstLI->getOperand(0);
- NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
-
- // Add all operands to the new PHI.
- for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
- Value *NewInVal = cast<LoadInst>(PN.getIncomingValue(i))->getOperand(0);
- if (NewInVal != InVal)
- InVal = 0;
- NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
- }
-
- Value *PhiVal;
- if (InVal) {
- // The new PHI unions all of the same values together. This is really
- // common, so we handle it intelligently here for compile-time speed.
- PhiVal = InVal;
- delete NewPN;
- } else {
- InsertNewInstBefore(NewPN, PN);
- PhiVal = NewPN;
- }
-
- // If this was a volatile load that we are merging, make sure to loop through
- // and mark all the input loads as non-volatile. If we don't do this, we will
- // insert a new volatile load and the old ones will not be deletable.
- if (isVolatile)
- for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
- cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false);
-
- return new LoadInst(PhiVal, "", isVolatile, LoadAlignment);
-}
-
-
-
-/// FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
-/// operator and they all are only used by the PHI, PHI together their
-/// inputs, and do the operation once, to the result of the PHI.
-Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
- Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
-
- if (isa<GetElementPtrInst>(FirstInst))
- return FoldPHIArgGEPIntoPHI(PN);
- if (isa<LoadInst>(FirstInst))
- return FoldPHIArgLoadIntoPHI(PN);
-
- // Scan the instruction, looking for input operations that can be folded away.
- // If all input operands to the phi are the same instruction (e.g. a cast from
- // the same type or "+42") we can pull the operation through the PHI, reducing
- // code size and simplifying code.
- Constant *ConstantOp = 0;
- const Type *CastSrcTy = 0;
-
- if (isa<CastInst>(FirstInst)) {
- CastSrcTy = FirstInst->getOperand(0)->getType();
-
- // Be careful about transforming integer PHIs. We don't want to pessimize
- // the code by turning an i32 into an i1293.
- if (isa<IntegerType>(PN.getType()) && isa<IntegerType>(CastSrcTy)) {
- if (!ShouldChangeType(PN.getType(), CastSrcTy, TD))
- return 0;
- }
- } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
- // Can fold binop, compare or shift here if the RHS is a constant,
- // otherwise call FoldPHIArgBinOpIntoPHI.
- ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
- if (ConstantOp == 0)
- return FoldPHIArgBinOpIntoPHI(PN);
- } else {
- return 0; // Cannot fold this operation.
- }
-
- // Check to see if all arguments are the same operation.
- for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
- Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
- if (I == 0 || !I->hasOneUse() || !I->isSameOperationAs(FirstInst))
- return 0;
- if (CastSrcTy) {
- if (I->getOperand(0)->getType() != CastSrcTy)
- return 0; // Cast operation must match.
- } else if (I->getOperand(1) != ConstantOp) {
- return 0;
- }
- }
-
- // Okay, they are all the same operation. Create a new PHI node of the
- // correct type, and PHI together all of the LHS's of the instructions.
- PHINode *NewPN = PHINode::Create(FirstInst->getOperand(0)->getType(),
- PN.getName()+".in");
- NewPN->reserveOperandSpace(PN.getNumOperands()/2);
-
- Value *InVal = FirstInst->getOperand(0);
- NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
-
- // Add all operands to the new PHI.
- for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
- Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
- if (NewInVal != InVal)
- InVal = 0;
- NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
- }
-
- Value *PhiVal;
- if (InVal) {
- // The new PHI unions all of the same values together. This is really
- // common, so we handle it intelligently here for compile-time speed.
- PhiVal = InVal;
- delete NewPN;
- } else {
- InsertNewInstBefore(NewPN, PN);
- PhiVal = NewPN;
- }
-
- // Insert and return the new operation.
- if (CastInst *FirstCI = dyn_cast<CastInst>(FirstInst))
- return CastInst::Create(FirstCI->getOpcode(), PhiVal, PN.getType());
-
- if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
- return BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp);
-
- CmpInst *CIOp = cast<CmpInst>(FirstInst);
- return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
- PhiVal, ConstantOp);
-}
-
-/// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
-/// that is dead.
-static bool DeadPHICycle(PHINode *PN,
- SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) {
- if (PN->use_empty()) return true;
- if (!PN->hasOneUse()) return false;
-
- // Remember this node, and if we find the cycle, return.
- if (!PotentiallyDeadPHIs.insert(PN))
- return true;
-
- // Don't scan crazily complex things.
- if (PotentiallyDeadPHIs.size() == 16)
- return false;
-
- if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
- return DeadPHICycle(PU, PotentiallyDeadPHIs);
-
- return false;
-}
-
-/// PHIsEqualValue - Return true if this phi node is always equal to
-/// NonPhiInVal. This happens with mutually cyclic phi nodes like:
-/// z = some value; x = phi (y, z); y = phi (x, z)
-static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal,
- SmallPtrSet<PHINode*, 16> &ValueEqualPHIs) {
- // See if we already saw this PHI node.
- if (!ValueEqualPHIs.insert(PN))
- return true;
-
- // Don't scan crazily complex things.
- if (ValueEqualPHIs.size() == 16)
- return false;
-
- // Scan the operands to see if they are either phi nodes or are equal to
- // the value.
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
- Value *Op = PN->getIncomingValue(i);
- if (PHINode *OpPN = dyn_cast<PHINode>(Op)) {
- if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs))
- return false;
- } else if (Op != NonPhiInVal)
- return false;
- }
-
- return true;
-}
-
-
-namespace {
-struct PHIUsageRecord {
- unsigned PHIId; // The ID # of the PHI (something determinstic to sort on)
- unsigned Shift; // The amount shifted.
- Instruction *Inst; // The trunc instruction.
-
- PHIUsageRecord(unsigned pn, unsigned Sh, Instruction *User)
- : PHIId(pn), Shift(Sh), Inst(User) {}
-
- bool operator<(const PHIUsageRecord &RHS) const {
- if (PHIId < RHS.PHIId) return true;
- if (PHIId > RHS.PHIId) return false;
- if (Shift < RHS.Shift) return true;
- if (Shift > RHS.Shift) return false;
- return Inst->getType()->getPrimitiveSizeInBits() <
- RHS.Inst->getType()->getPrimitiveSizeInBits();
- }
-};
-
-struct LoweredPHIRecord {
- PHINode *PN; // The PHI that was lowered.
- unsigned Shift; // The amount shifted.
- unsigned Width; // The width extracted.
-
- LoweredPHIRecord(PHINode *pn, unsigned Sh, const Type *Ty)
- : PN(pn), Shift(Sh), Width(Ty->getPrimitiveSizeInBits()) {}
-
- // Ctor form used by DenseMap.
- LoweredPHIRecord(PHINode *pn, unsigned Sh)
- : PN(pn), Shift(Sh), Width(0) {}
-};
-}
-
-namespace llvm {
- template<>
- struct DenseMapInfo<LoweredPHIRecord> {
- static inline LoweredPHIRecord getEmptyKey() {
- return LoweredPHIRecord(0, 0);
- }
- static inline LoweredPHIRecord getTombstoneKey() {
- return LoweredPHIRecord(0, 1);
- }
- static unsigned getHashValue(const LoweredPHIRecord &Val) {
- return DenseMapInfo<PHINode*>::getHashValue(Val.PN) ^ (Val.Shift>>3) ^
- (Val.Width>>3);
- }
- static bool isEqual(const LoweredPHIRecord &LHS,
- const LoweredPHIRecord &RHS) {
- return LHS.PN == RHS.PN && LHS.Shift == RHS.Shift &&
- LHS.Width == RHS.Width;
- }
- };
- template <>
- struct isPodLike<LoweredPHIRecord> { static const bool value = true; };
-}
-
-
-/// SliceUpIllegalIntegerPHI - This is an integer PHI and we know that it has an
-/// illegal type: see if it is only used by trunc or trunc(lshr) operations. If
-/// so, we split the PHI into the various pieces being extracted. This sort of
-/// thing is introduced when SROA promotes an aggregate to large integer values.
-///
-/// TODO: The user of the trunc may be an bitcast to float/double/vector or an
-/// inttoptr. We should produce new PHIs in the right type.
-///
-Instruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &FirstPhi) {
- // PHIUsers - Keep track of all of the truncated values extracted from a set
- // of PHIs, along with their offset. These are the things we want to rewrite.
- SmallVector<PHIUsageRecord, 16> PHIUsers;
-
- // PHIs are often mutually cyclic, so we keep track of a whole set of PHI
- // nodes which are extracted from. PHIsToSlice is a set we use to avoid
- // revisiting PHIs, PHIsInspected is a ordered list of PHIs that we need to
- // check the uses of (to ensure they are all extracts).
- SmallVector<PHINode*, 8> PHIsToSlice;
- SmallPtrSet<PHINode*, 8> PHIsInspected;
-
- PHIsToSlice.push_back(&FirstPhi);
- PHIsInspected.insert(&FirstPhi);
-
- for (unsigned PHIId = 0; PHIId != PHIsToSlice.size(); ++PHIId) {
- PHINode *PN = PHIsToSlice[PHIId];
-
- // Scan the input list of the PHI. If any input is an invoke, and if the
- // input is defined in the predecessor, then we won't be split the critical
- // edge which is required to insert a truncate. Because of this, we have to
- // bail out.
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
- InvokeInst *II = dyn_cast<InvokeInst>(PN->getIncomingValue(i));
- if (II == 0) continue;
- if (II->getParent() != PN->getIncomingBlock(i))
- continue;
-
- // If we have a phi, and if it's directly in the predecessor, then we have
- // a critical edge where we need to put the truncate. Since we can't
- // split the edge in instcombine, we have to bail out.
- return 0;
- }
-
-
- for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end();
- UI != E; ++UI) {
- Instruction *User = cast<Instruction>(*UI);
-
- // If the user is a PHI, inspect its uses recursively.
- if (PHINode *UserPN = dyn_cast<PHINode>(User)) {
- if (PHIsInspected.insert(UserPN))
- PHIsToSlice.push_back(UserPN);
- continue;
- }
-
- // Truncates are always ok.
- if (isa<TruncInst>(User)) {
- PHIUsers.push_back(PHIUsageRecord(PHIId, 0, User));
- continue;
- }
-
- // Otherwise it must be a lshr which can only be used by one trunc.
- if (User->getOpcode() != Instruction::LShr ||
- !User->hasOneUse() || !isa<TruncInst>(User->use_back()) ||
- !isa<ConstantInt>(User->getOperand(1)))
- return 0;
-
- unsigned Shift = cast<ConstantInt>(User->getOperand(1))->getZExtValue();
- PHIUsers.push_back(PHIUsageRecord(PHIId, Shift, User->use_back()));
- }
- }
-
- // If we have no users, they must be all self uses, just nuke the PHI.
- if (PHIUsers.empty())
- return ReplaceInstUsesWith(FirstPhi, UndefValue::get(FirstPhi.getType()));
-
- // If this phi node is transformable, create new PHIs for all the pieces
- // extracted out of it. First, sort the users by their offset and size.
- array_pod_sort(PHIUsers.begin(), PHIUsers.end());
-
- DEBUG(errs() << "SLICING UP PHI: " << FirstPhi << '\n';
- for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i)
- errs() << "AND USER PHI #" << i << ": " << *PHIsToSlice[i] <<'\n';
- );
-
- // PredValues - This is a temporary used when rewriting PHI nodes. It is
- // hoisted out here to avoid construction/destruction thrashing.
- DenseMap<BasicBlock*, Value*> PredValues;
-
- // ExtractedVals - Each new PHI we introduce is saved here so we don't
- // introduce redundant PHIs.
- DenseMap<LoweredPHIRecord, PHINode*> ExtractedVals;
-
- for (unsigned UserI = 0, UserE = PHIUsers.size(); UserI != UserE; ++UserI) {
- unsigned PHIId = PHIUsers[UserI].PHIId;
- PHINode *PN = PHIsToSlice[PHIId];
- unsigned Offset = PHIUsers[UserI].Shift;
- const Type *Ty = PHIUsers[UserI].Inst->getType();
-
- PHINode *EltPHI;
-
- // If we've already lowered a user like this, reuse the previously lowered
- // value.
- if ((EltPHI = ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)]) == 0) {
-
- // Otherwise, Create the new PHI node for this user.
- EltPHI = PHINode::Create(Ty, PN->getName()+".off"+Twine(Offset), PN);
- assert(EltPHI->getType() != PN->getType() &&
- "Truncate didn't shrink phi?");
-
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
- BasicBlock *Pred = PN->getIncomingBlock(i);
- Value *&PredVal = PredValues[Pred];
-
- // If we already have a value for this predecessor, reuse it.
- if (PredVal) {
- EltPHI->addIncoming(PredVal, Pred);
- continue;
- }
-
- // Handle the PHI self-reuse case.
- Value *InVal = PN->getIncomingValue(i);
- if (InVal == PN) {
- PredVal = EltPHI;
- EltPHI->addIncoming(PredVal, Pred);
- continue;
- }
-
- if (PHINode *InPHI = dyn_cast<PHINode>(PN)) {
- // If the incoming value was a PHI, and if it was one of the PHIs we
- // already rewrote it, just use the lowered value.
- if (Value *Res = ExtractedVals[LoweredPHIRecord(InPHI, Offset, Ty)]) {
- PredVal = Res;
- EltPHI->addIncoming(PredVal, Pred);
- continue;
- }
- }
-
- // Otherwise, do an extract in the predecessor.
- Builder->SetInsertPoint(Pred, Pred->getTerminator());
- Value *Res = InVal;
- if (Offset)
- Res = Builder->CreateLShr(Res, ConstantInt::get(InVal->getType(),
- Offset), "extract");
- Res = Builder->CreateTrunc(Res, Ty, "extract.t");
- PredVal = Res;
- EltPHI->addIncoming(Res, Pred);
-
- // If the incoming value was a PHI, and if it was one of the PHIs we are
- // rewriting, we will ultimately delete the code we inserted. This
- // means we need to revisit that PHI to make sure we extract out the
- // needed piece.
- if (PHINode *OldInVal = dyn_cast<PHINode>(PN->getIncomingValue(i)))
- if (PHIsInspected.count(OldInVal)) {
- unsigned RefPHIId = std::find(PHIsToSlice.begin(),PHIsToSlice.end(),
- OldInVal)-PHIsToSlice.begin();
- PHIUsers.push_back(PHIUsageRecord(RefPHIId, Offset,
- cast<Instruction>(Res)));
- ++UserE;
- }
- }
- PredValues.clear();
-
- DEBUG(errs() << " Made element PHI for offset " << Offset << ": "
- << *EltPHI << '\n');
- ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)] = EltPHI;
- }
-
- // Replace the use of this piece with the PHI node.
- ReplaceInstUsesWith(*PHIUsers[UserI].Inst, EltPHI);
- }
-
- // Replace all the remaining uses of the PHI nodes (self uses and the lshrs)
- // with undefs.
- Value *Undef = UndefValue::get(FirstPhi.getType());
- for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i)
- ReplaceInstUsesWith(*PHIsToSlice[i], Undef);
- return ReplaceInstUsesWith(FirstPhi, Undef);
-}
-
-// PHINode simplification
-//
-Instruction *InstCombiner::visitPHINode(PHINode &PN) {
- // If LCSSA is around, don't mess with Phi nodes
- if (MustPreserveLCSSA) return 0;
-
- if (Value *V = PN.hasConstantValue())
- return ReplaceInstUsesWith(PN, V);
-
- // If all PHI operands are the same operation, pull them through the PHI,
- // reducing code size.
- if (isa<Instruction>(PN.getIncomingValue(0)) &&
- isa<Instruction>(PN.getIncomingValue(1)) &&
- cast<Instruction>(PN.getIncomingValue(0))->getOpcode() ==
- cast<Instruction>(PN.getIncomingValue(1))->getOpcode() &&
- // FIXME: The hasOneUse check will fail for PHIs that use the value more
- // than themselves more than once.
- PN.getIncomingValue(0)->hasOneUse())
- if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
- return Result;
-
- // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
- // this PHI only has a single use (a PHI), and if that PHI only has one use (a
- // PHI)... break the cycle.
- if (PN.hasOneUse()) {
- Instruction *PHIUser = cast<Instruction>(PN.use_back());
- if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) {
- SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs;
- PotentiallyDeadPHIs.insert(&PN);
- if (DeadPHICycle(PU, PotentiallyDeadPHIs))
- return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
- }
-
- // If this phi has a single use, and if that use just computes a value for
- // the next iteration of a loop, delete the phi. This occurs with unused
- // induction variables, e.g. "for (int j = 0; ; ++j);". Detecting this
- // common case here is good because the only other things that catch this
- // are induction variable analysis (sometimes) and ADCE, which is only run
- // late.
- if (PHIUser->hasOneUse() &&
- (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) &&
- PHIUser->use_back() == &PN) {
- return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
- }
- }
-
- // We sometimes end up with phi cycles that non-obviously end up being the
- // same value, for example:
- // z = some value; x = phi (y, z); y = phi (x, z)
- // where the phi nodes don't necessarily need to be in the same block. Do a
- // quick check to see if the PHI node only contains a single non-phi value, if
- // so, scan to see if the phi cycle is actually equal to that value.
- {
- unsigned InValNo = 0, NumOperandVals = PN.getNumIncomingValues();
- // Scan for the first non-phi operand.
- while (InValNo != NumOperandVals &&
- isa<PHINode>(PN.getIncomingValue(InValNo)))
- ++InValNo;
-
- if (InValNo != NumOperandVals) {
- Value *NonPhiInVal = PN.getOperand(InValNo);
-
- // Scan the rest of the operands to see if there are any conflicts, if so
- // there is no need to recursively scan other phis.
- for (++InValNo; InValNo != NumOperandVals; ++InValNo) {
- Value *OpVal = PN.getIncomingValue(InValNo);
- if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal))
- break;
- }
-
- // If we scanned over all operands, then we have one unique value plus
- // phi values. Scan PHI nodes to see if they all merge in each other or
- // the value.
- if (InValNo == NumOperandVals) {
- SmallPtrSet<PHINode*, 16> ValueEqualPHIs;
- if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs))
- return ReplaceInstUsesWith(PN, NonPhiInVal);
- }
- }
- }
-
- // If there are multiple PHIs, sort their operands so that they all list
- // the blocks in the same order. This will help identical PHIs be eliminated
- // by other passes. Other passes shouldn't depend on this for correctness
- // however.
- PHINode *FirstPN = cast<PHINode>(PN.getParent()->begin());
- if (&PN != FirstPN)
- for (unsigned i = 0, e = FirstPN->getNumIncomingValues(); i != e; ++i) {
- BasicBlock *BBA = PN.getIncomingBlock(i);
- BasicBlock *BBB = FirstPN->getIncomingBlock(i);
- if (BBA != BBB) {
- Value *VA = PN.getIncomingValue(i);
- unsigned j = PN.getBasicBlockIndex(BBB);
- Value *VB = PN.getIncomingValue(j);
- PN.setIncomingBlock(i, BBB);
- PN.setIncomingValue(i, VB);
- PN.setIncomingBlock(j, BBA);
- PN.setIncomingValue(j, VA);
- // NOTE: Instcombine normally would want us to "return &PN" if we
- // modified any of the operands of an instruction. However, since we
- // aren't adding or removing uses (just rearranging them) we don't do
- // this in this case.
- }
- }
-
- // If this is an integer PHI and we know that it has an illegal type, see if
- // it is only used by trunc or trunc(lshr) operations. If so, we split the
- // PHI into the various pieces being extracted. This sort of thing is
- // introduced when SROA promotes an aggregate to a single large integer type.
- if (isa<IntegerType>(PN.getType()) && TD &&
- !TD->isLegalInteger(PN.getType()->getPrimitiveSizeInBits()))
- if (Instruction *Res = SliceUpIllegalIntegerPHI(PN))
- return Res;
-
- return 0;
-}
-
-Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
- SmallVector<Value*, 8> Ops(GEP.op_begin(), GEP.op_end());
-
- if (Value *V = SimplifyGEPInst(&Ops[0], Ops.size(), TD))
- return ReplaceInstUsesWith(GEP, V);
-
- Value *PtrOp = GEP.getOperand(0);
-
- if (isa<UndefValue>(GEP.getOperand(0)))
- return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
-
- // Eliminate unneeded casts for indices.
- if (TD) {
- bool MadeChange = false;
- unsigned PtrSize = TD->getPointerSizeInBits();
-
- gep_type_iterator GTI = gep_type_begin(GEP);
- for (User::op_iterator I = GEP.op_begin() + 1, E = GEP.op_end();
- I != E; ++I, ++GTI) {
- if (!isa<SequentialType>(*GTI)) continue;
-
- // If we are using a wider index than needed for this platform, shrink it
- // to what we need. If narrower, sign-extend it to what we need. This
- // explicit cast can make subsequent optimizations more obvious.
- unsigned OpBits = cast<IntegerType>((*I)->getType())->getBitWidth();
- if (OpBits == PtrSize)
- continue;
-
- *I = Builder->CreateIntCast(*I, TD->getIntPtrType(GEP.getContext()),true);
- MadeChange = true;
- }
- if (MadeChange) return &GEP;
- }
-
- // Combine Indices - If the source pointer to this getelementptr instruction
- // is a getelementptr instruction, combine the indices of the two
- // getelementptr instructions into a single instruction.
- //
- if (GEPOperator *Src = dyn_cast<GEPOperator>(PtrOp)) {
- // Note that if our source is a gep chain itself that we wait for that
- // chain to be resolved before we perform this transformation. This
- // avoids us creating a TON of code in some cases.
- //
- if (GetElementPtrInst *SrcGEP =
- dyn_cast<GetElementPtrInst>(Src->getOperand(0)))
- if (SrcGEP->getNumOperands() == 2)
- return 0; // Wait until our source is folded to completion.
-
- SmallVector<Value*, 8> Indices;
-
- // Find out whether the last index in the source GEP is a sequential idx.
- bool EndsWithSequential = false;
- for (gep_type_iterator I = gep_type_begin(*Src), E = gep_type_end(*Src);
- I != E; ++I)
- EndsWithSequential = !isa<StructType>(*I);
-
- // Can we combine the two pointer arithmetics offsets?
- if (EndsWithSequential) {
- // Replace: gep (gep %P, long B), long A, ...
- // With: T = long A+B; gep %P, T, ...
- //
- Value *Sum;
- Value *SO1 = Src->getOperand(Src->getNumOperands()-1);
- Value *GO1 = GEP.getOperand(1);
- if (SO1 == Constant::getNullValue(SO1->getType())) {
- Sum = GO1;
- } else if (GO1 == Constant::getNullValue(GO1->getType())) {
- Sum = SO1;
- } else {
- // If they aren't the same type, then the input hasn't been processed
- // by the loop above yet (which canonicalizes sequential index types to
- // intptr_t). Just avoid transforming this until the input has been
- // normalized.
- if (SO1->getType() != GO1->getType())
- return 0;
- Sum = Builder->CreateAdd(SO1, GO1, PtrOp->getName()+".sum");
- }
-
- // Update the GEP in place if possible.
- if (Src->getNumOperands() == 2) {
- GEP.setOperand(0, Src->getOperand(0));
- GEP.setOperand(1, Sum);
- return &GEP;
- }
- Indices.append(Src->op_begin()+1, Src->op_end()-1);
- Indices.push_back(Sum);
- Indices.append(GEP.op_begin()+2, GEP.op_end());
- } else if (isa<Constant>(*GEP.idx_begin()) &&
- cast<Constant>(*GEP.idx_begin())->isNullValue() &&
- Src->getNumOperands() != 1) {
- // Otherwise we can do the fold if the first index of the GEP is a zero
- Indices.append(Src->op_begin()+1, Src->op_end());
- Indices.append(GEP.idx_begin()+1, GEP.idx_end());
- }
-
- if (!Indices.empty())
- return (cast<GEPOperator>(&GEP)->isInBounds() &&
- Src->isInBounds()) ?
- GetElementPtrInst::CreateInBounds(Src->getOperand(0), Indices.begin(),
- Indices.end(), GEP.getName()) :
- GetElementPtrInst::Create(Src->getOperand(0), Indices.begin(),
- Indices.end(), GEP.getName());
- }
-
- // Handle gep(bitcast x) and gep(gep x, 0, 0, 0).
- if (Value *X = getBitCastOperand(PtrOp)) {
- assert(isa<PointerType>(X->getType()) && "Must be cast from pointer");
-
- // If the input bitcast is actually "bitcast(bitcast(x))", then we don't
- // want to change the gep until the bitcasts are eliminated.
- if (getBitCastOperand(X)) {
- Worklist.AddValue(PtrOp);
- return 0;
- }
-
- bool HasZeroPointerIndex = false;
- if (ConstantInt *C = dyn_cast<ConstantInt>(GEP.getOperand(1)))
- HasZeroPointerIndex = C->isZero();
-
- // Transform: GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ...
- // into : GEP [10 x i8]* X, i32 0, ...
- //
- // Likewise, transform: GEP (bitcast i8* X to [0 x i8]*), i32 0, ...
- // into : GEP i8* X, ...
- //
- // This occurs when the program declares an array extern like "int X[];"
- if (HasZeroPointerIndex) {
- const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
- const PointerType *XTy = cast<PointerType>(X->getType());
- if (const ArrayType *CATy =
- dyn_cast<ArrayType>(CPTy->getElementType())) {
- // GEP (bitcast i8* X to [0 x i8]*), i32 0, ... ?
- if (CATy->getElementType() == XTy->getElementType()) {
- // -> GEP i8* X, ...
- SmallVector<Value*, 8> Indices(GEP.idx_begin()+1, GEP.idx_end());
- return cast<GEPOperator>(&GEP)->isInBounds() ?
- GetElementPtrInst::CreateInBounds(X, Indices.begin(), Indices.end(),
- GEP.getName()) :
- GetElementPtrInst::Create(X, Indices.begin(), Indices.end(),
- GEP.getName());
- }
-
- if (const ArrayType *XATy = dyn_cast<ArrayType>(XTy->getElementType())){
- // GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ... ?
- if (CATy->getElementType() == XATy->getElementType()) {
- // -> GEP [10 x i8]* X, i32 0, ...
- // At this point, we know that the cast source type is a pointer
- // to an array of the same type as the destination pointer
- // array. Because the array type is never stepped over (there
- // is a leading zero) we can fold the cast into this GEP.
- GEP.setOperand(0, X);
- return &GEP;
- }
- }
- }
- } else if (GEP.getNumOperands() == 2) {
- // Transform things like:
- // %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V
- // into: %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast
- const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
- const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
- if (TD && isa<ArrayType>(SrcElTy) &&
- TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
- TD->getTypeAllocSize(ResElTy)) {
- Value *Idx[2];
- Idx[0] = Constant::getNullValue(Type::getInt32Ty(*Context));
- Idx[1] = GEP.getOperand(1);
- Value *NewGEP = cast<GEPOperator>(&GEP)->isInBounds() ?
- Builder->CreateInBoundsGEP(X, Idx, Idx + 2, GEP.getName()) :
- Builder->CreateGEP(X, Idx, Idx + 2, GEP.getName());
- // V and GEP are both pointer types --> BitCast
- return new BitCastInst(NewGEP, GEP.getType());
- }
-
- // Transform things like:
- // getelementptr i8* bitcast ([100 x double]* X to i8*), i32 %tmp
- // (where tmp = 8*tmp2) into:
- // getelementptr [100 x double]* %arr, i32 0, i32 %tmp2; bitcast
-
- if (TD && isa<ArrayType>(SrcElTy) && ResElTy == Type::getInt8Ty(*Context)) {
- uint64_t ArrayEltSize =
- TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType());
-
- // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
- // allow either a mul, shift, or constant here.
- Value *NewIdx = 0;
- ConstantInt *Scale = 0;
- if (ArrayEltSize == 1) {
- NewIdx = GEP.getOperand(1);
- Scale = ConstantInt::get(cast<IntegerType>(NewIdx->getType()), 1);
- } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
- NewIdx = ConstantInt::get(CI->getType(), 1);
- Scale = CI;
- } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
- if (Inst->getOpcode() == Instruction::Shl &&
- isa<ConstantInt>(Inst->getOperand(1))) {
- ConstantInt *ShAmt = cast<ConstantInt>(Inst->getOperand(1));
- uint32_t ShAmtVal = ShAmt->getLimitedValue(64);
- Scale = ConstantInt::get(cast<IntegerType>(Inst->getType()),
- 1ULL << ShAmtVal);
- NewIdx = Inst->getOperand(0);
- } else if (Inst->getOpcode() == Instruction::Mul &&
- isa<ConstantInt>(Inst->getOperand(1))) {
- Scale = cast<ConstantInt>(Inst->getOperand(1));
- NewIdx = Inst->getOperand(0);
- }
- }
-
- // If the index will be to exactly the right offset with the scale taken
- // out, perform the transformation. Note, we don't know whether Scale is
- // signed or not. We'll use unsigned version of division/modulo
- // operation after making sure Scale doesn't have the sign bit set.
- if (ArrayEltSize && Scale && Scale->getSExtValue() >= 0LL &&
- Scale->getZExtValue() % ArrayEltSize == 0) {
- Scale = ConstantInt::get(Scale->getType(),
- Scale->getZExtValue() / ArrayEltSize);
- if (Scale->getZExtValue() != 1) {
- Constant *C = ConstantExpr::getIntegerCast(Scale, NewIdx->getType(),
- false /*ZExt*/);
- NewIdx = Builder->CreateMul(NewIdx, C, "idxscale");
- }
-
- // Insert the new GEP instruction.
- Value *Idx[2];
- Idx[0] = Constant::getNullValue(Type::getInt32Ty(*Context));
- Idx[1] = NewIdx;
- Value *NewGEP = cast<GEPOperator>(&GEP)->isInBounds() ?
- Builder->CreateInBoundsGEP(X, Idx, Idx + 2, GEP.getName()) :
- Builder->CreateGEP(X, Idx, Idx + 2, GEP.getName());
- // The NewGEP must be pointer typed, so must the old one -> BitCast
- return new BitCastInst(NewGEP, GEP.getType());
- }
- }
- }
- }
-
- /// See if we can simplify:
- /// X = bitcast A* to B*
- /// Y = gep X, <...constant indices...>
- /// into a gep of the original struct. This is important for SROA and alias
- /// analysis of unions. If "A" is also a bitcast, wait for A/X to be merged.
- if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
- if (TD &&
- !isa<BitCastInst>(BCI->getOperand(0)) && GEP.hasAllConstantIndices()) {
- // Determine how much the GEP moves the pointer. We are guaranteed to get
- // a constant back from EmitGEPOffset.
- ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(&GEP, *this));
- int64_t Offset = OffsetV->getSExtValue();
-
- // If this GEP instruction doesn't move the pointer, just replace the GEP
- // with a bitcast of the real input to the dest type.
- if (Offset == 0) {
- // If the bitcast is of an allocation, and the allocation will be
- // converted to match the type of the cast, don't touch this.
- if (isa<AllocaInst>(BCI->getOperand(0)) ||
- isMalloc(BCI->getOperand(0))) {
- // See if the bitcast simplifies, if so, don't nuke this GEP yet.
- if (Instruction *I = visitBitCast(*BCI)) {
- if (I != BCI) {
- I->takeName(BCI);
- BCI->getParent()->getInstList().insert(BCI, I);
- ReplaceInstUsesWith(*BCI, I);
- }
- return &GEP;
- }
- }
- return new BitCastInst(BCI->getOperand(0), GEP.getType());
- }
-
- // Otherwise, if the offset is non-zero, we need to find out if there is a
- // field at Offset in 'A's type. If so, we can pull the cast through the
- // GEP.
- SmallVector<Value*, 8> NewIndices;
- const Type *InTy =
- cast<PointerType>(BCI->getOperand(0)->getType())->getElementType();
- if (FindElementAtOffset(InTy, Offset, NewIndices, TD, Context)) {
- Value *NGEP = cast<GEPOperator>(&GEP)->isInBounds() ?
- Builder->CreateInBoundsGEP(BCI->getOperand(0), NewIndices.begin(),
- NewIndices.end()) :
- Builder->CreateGEP(BCI->getOperand(0), NewIndices.begin(),
- NewIndices.end());
-
- if (NGEP->getType() == GEP.getType())
- return ReplaceInstUsesWith(GEP, NGEP);
- NGEP->takeName(&GEP);
- return new BitCastInst(NGEP, GEP.getType());
- }
- }
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) {
- // Convert: alloca Ty, C - where C is a constant != 1 into: alloca [C x Ty], 1
- if (AI.isArrayAllocation()) { // Check C != 1
- if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
- const Type *NewTy =
- ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
- assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
- AllocaInst *New = Builder->CreateAlloca(NewTy, 0, AI.getName());
- New->setAlignment(AI.getAlignment());
-
- // Scan to the end of the allocation instructions, to skip over a block of
- // allocas if possible...also skip interleaved debug info
- //
- BasicBlock::iterator It = New;
- while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It)) ++It;
-
- // Now that I is pointing to the first non-allocation-inst in the block,
- // insert our getelementptr instruction...
- //
- Value *NullIdx = Constant::getNullValue(Type::getInt32Ty(*Context));
- Value *Idx[2];
- Idx[0] = NullIdx;
- Idx[1] = NullIdx;
- Value *V = GetElementPtrInst::CreateInBounds(New, Idx, Idx + 2,
- New->getName()+".sub", It);
-
- // Now make everything use the getelementptr instead of the original
- // allocation.
- return ReplaceInstUsesWith(AI, V);
- } else if (isa<UndefValue>(AI.getArraySize())) {
- return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
- }
- }
-
- if (TD && isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized()) {
- // If alloca'ing a zero byte object, replace the alloca with a null pointer.
- // Note that we only do this for alloca's, because malloc should allocate
- // and return a unique pointer, even for a zero byte allocation.
- if (TD->getTypeAllocSize(AI.getAllocatedType()) == 0)
- return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
-
- // If the alignment is 0 (unspecified), assign it the preferred alignment.
- if (AI.getAlignment() == 0)
- AI.setAlignment(TD->getPrefTypeAlignment(AI.getAllocatedType()));
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitFree(Instruction &FI) {
- Value *Op = FI.getOperand(1);
-
- // free undef -> unreachable.
- if (isa<UndefValue>(Op)) {
- // Insert a new store to null because we cannot modify the CFG here.
- new StoreInst(ConstantInt::getTrue(*Context),
- UndefValue::get(Type::getInt1PtrTy(*Context)), &FI);
- return EraseInstFromFunction(FI);
- }
-
- // If we have 'free null' delete the instruction. This can happen in stl code
- // when lots of inlining happens.
- if (isa<ConstantPointerNull>(Op))
- return EraseInstFromFunction(FI);
-
- // If we have a malloc call whose only use is a free call, delete both.
- if (isMalloc(Op)) {
- if (CallInst* CI = extractMallocCallFromBitCast(Op)) {
- if (Op->hasOneUse() && CI->hasOneUse()) {
- EraseInstFromFunction(FI);
- EraseInstFromFunction(*CI);
- return EraseInstFromFunction(*cast<Instruction>(Op));
- }
- } else {
- // Op is a call to malloc
- if (Op->hasOneUse()) {
- EraseInstFromFunction(FI);
- return EraseInstFromFunction(*cast<Instruction>(Op));
- }
- }
- }
-
- return 0;
-}
-
-/// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
-static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
- const TargetData *TD) {
- User *CI = cast<User>(LI.getOperand(0));
- Value *CastOp = CI->getOperand(0);
- LLVMContext *Context = IC.getContext();
-
- const PointerType *DestTy = cast<PointerType>(CI->getType());
- const Type *DestPTy = DestTy->getElementType();
- if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
-
- // If the address spaces don't match, don't eliminate the cast.
- if (DestTy->getAddressSpace() != SrcTy->getAddressSpace())
- return 0;
-
- const Type *SrcPTy = SrcTy->getElementType();
-
- if (DestPTy->isInteger() || isa<PointerType>(DestPTy) ||
- isa<VectorType>(DestPTy)) {
- // If the source is an array, the code below will not succeed. Check to
- // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
- // constants.
- if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
- if (Constant *CSrc = dyn_cast<Constant>(CastOp))
- if (ASrcTy->getNumElements() != 0) {
- Value *Idxs[2];
- Idxs[0] = Constant::getNullValue(Type::getInt32Ty(*Context));
- Idxs[1] = Idxs[0];
- CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
- SrcTy = cast<PointerType>(CastOp->getType());
- SrcPTy = SrcTy->getElementType();
- }
-
- if (IC.getTargetData() &&
- (SrcPTy->isInteger() || isa<PointerType>(SrcPTy) ||
- isa<VectorType>(SrcPTy)) &&
- // Do not allow turning this into a load of an integer, which is then
- // casted to a pointer, this pessimizes pointer analysis a lot.
- (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
- IC.getTargetData()->getTypeSizeInBits(SrcPTy) ==
- IC.getTargetData()->getTypeSizeInBits(DestPTy)) {
-
- // Okay, we are casting from one integer or pointer type to another of
- // the same size. Instead of casting the pointer before the load, cast
- // the result of the loaded value.
- Value *NewLoad =
- IC.Builder->CreateLoad(CastOp, LI.isVolatile(), CI->getName());
- // Now cast the result of the load.
- return new BitCastInst(NewLoad, LI.getType());
- }
- }
- }
- return 0;
-}
-
-Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
- Value *Op = LI.getOperand(0);
-
- // Attempt to improve the alignment.
- if (TD) {
- unsigned KnownAlign =
- GetOrEnforceKnownAlignment(Op, TD->getPrefTypeAlignment(LI.getType()));
- if (KnownAlign >
- (LI.getAlignment() == 0 ? TD->getABITypeAlignment(LI.getType()) :
- LI.getAlignment()))
- LI.setAlignment(KnownAlign);
- }
-
- // load (cast X) --> cast (load X) iff safe.
- if (isa<CastInst>(Op))
- if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
- return Res;
-
- // None of the following transforms are legal for volatile loads.
- if (LI.isVolatile()) return 0;
-
- // Do really simple store-to-load forwarding and load CSE, to catch cases
- // where there are several consequtive memory accesses to the same location,
- // separated by a few arithmetic operations.
- BasicBlock::iterator BBI = &LI;
- if (Value *AvailableVal = FindAvailableLoadedValue(Op, LI.getParent(), BBI,6))
- return ReplaceInstUsesWith(LI, AvailableVal);
-
- // load(gep null, ...) -> unreachable
- if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
- const Value *GEPI0 = GEPI->getOperand(0);
- // TODO: Consider a target hook for valid address spaces for this xform.
- if (isa<ConstantPointerNull>(GEPI0) && GEPI->getPointerAddressSpace() == 0){
- // Insert a new store to null instruction before the load to indicate
- // that this code is not reachable. We do this instead of inserting
- // an unreachable instruction directly because we cannot modify the
- // CFG.
- new StoreInst(UndefValue::get(LI.getType()),
- Constant::getNullValue(Op->getType()), &LI);
- return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
- }
- }
-
- // load null/undef -> unreachable
- // TODO: Consider a target hook for valid address spaces for this xform.
- if (isa<UndefValue>(Op) ||
- (isa<ConstantPointerNull>(Op) && LI.getPointerAddressSpace() == 0)) {
- // Insert a new store to null instruction before the load to indicate that
- // this code is not reachable. We do this instead of inserting an
- // unreachable instruction directly because we cannot modify the CFG.
- new StoreInst(UndefValue::get(LI.getType()),
- Constant::getNullValue(Op->getType()), &LI);
- return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
- }
-
- // Instcombine load (constantexpr_cast global) -> cast (load global)
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
- if (CE->isCast())
- if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
- return Res;
-
- if (Op->hasOneUse()) {
- // Change select and PHI nodes to select values instead of addresses: this
- // helps alias analysis out a lot, allows many others simplifications, and
- // exposes redundancy in the code.
- //
- // Note that we cannot do the transformation unless we know that the
- // introduced loads cannot trap! Something like this is valid as long as
- // the condition is always false: load (select bool %C, int* null, int* %G),
- // but it would not be valid if we transformed it to load from null
- // unconditionally.
- //
- if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
- // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
- if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
- isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
- Value *V1 = Builder->CreateLoad(SI->getOperand(1),
- SI->getOperand(1)->getName()+".val");
- Value *V2 = Builder->CreateLoad(SI->getOperand(2),
- SI->getOperand(2)->getName()+".val");
- return SelectInst::Create(SI->getCondition(), V1, V2);
- }
-
- // load (select (cond, null, P)) -> load P
- if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
- if (C->isNullValue()) {
- LI.setOperand(0, SI->getOperand(2));
- return &LI;
- }
-
- // load (select (cond, P, null)) -> load P
- if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
- if (C->isNullValue()) {
- LI.setOperand(0, SI->getOperand(1));
- return &LI;
- }
- }
- }
- return 0;
-}
-
-/// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast V), P
-/// when possible. This makes it generally easy to do alias analysis and/or
-/// SROA/mem2reg of the memory object.
-static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
- User *CI = cast<User>(SI.getOperand(1));
- Value *CastOp = CI->getOperand(0);
-
- const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
- const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType());
- if (SrcTy == 0) return 0;
-
- const Type *SrcPTy = SrcTy->getElementType();
-
- if (!DestPTy->isInteger() && !isa<PointerType>(DestPTy))
- return 0;
-
- /// NewGEPIndices - If SrcPTy is an aggregate type, we can emit a "noop gep"
- /// to its first element. This allows us to handle things like:
- /// store i32 xxx, (bitcast {foo*, float}* %P to i32*)
- /// on 32-bit hosts.
- SmallVector<Value*, 4> NewGEPIndices;
-
- // If the source is an array, the code below will not succeed. Check to
- // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
- // constants.
- if (isa<ArrayType>(SrcPTy) || isa<StructType>(SrcPTy)) {
- // Index through pointer.
- Constant *Zero = Constant::getNullValue(Type::getInt32Ty(*IC.getContext()));
- NewGEPIndices.push_back(Zero);
-
- while (1) {
- if (const StructType *STy = dyn_cast<StructType>(SrcPTy)) {
- if (!STy->getNumElements()) /* Struct can be empty {} */
- break;
- NewGEPIndices.push_back(Zero);
- SrcPTy = STy->getElementType(0);
- } else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcPTy)) {
- NewGEPIndices.push_back(Zero);
- SrcPTy = ATy->getElementType();
- } else {
- break;
- }
- }
-
- SrcTy = PointerType::get(SrcPTy, SrcTy->getAddressSpace());
- }
-
- if (!SrcPTy->isInteger() && !isa<PointerType>(SrcPTy))
- return 0;
-
- // If the pointers point into different address spaces or if they point to
- // values with different sizes, we can't do the transformation.
- if (!IC.getTargetData() ||
- SrcTy->getAddressSpace() !=
- cast<PointerType>(CI->getType())->getAddressSpace() ||
- IC.getTargetData()->getTypeSizeInBits(SrcPTy) !=
- IC.getTargetData()->getTypeSizeInBits(DestPTy))
- return 0;
-
- // Okay, we are casting from one integer or pointer type to another of
- // the same size. Instead of casting the pointer before
- // the store, cast the value to be stored.
- Value *NewCast;
- Value *SIOp0 = SI.getOperand(0);
- Instruction::CastOps opcode = Instruction::BitCast;
- const Type* CastSrcTy = SIOp0->getType();
- const Type* CastDstTy = SrcPTy;
- if (isa<PointerType>(CastDstTy)) {
- if (CastSrcTy->isInteger())
- opcode = Instruction::IntToPtr;
- } else if (isa<IntegerType>(CastDstTy)) {
- if (isa<PointerType>(SIOp0->getType()))
- opcode = Instruction::PtrToInt;
- }
-
- // SIOp0 is a pointer to aggregate and this is a store to the first field,
- // emit a GEP to index into its first field.
- if (!NewGEPIndices.empty())
- CastOp = IC.Builder->CreateInBoundsGEP(CastOp, NewGEPIndices.begin(),
- NewGEPIndices.end());
-
- NewCast = IC.Builder->CreateCast(opcode, SIOp0, CastDstTy,
- SIOp0->getName()+".c");
- return new StoreInst(NewCast, CastOp);
-}
-
-/// equivalentAddressValues - Test if A and B will obviously have the same
-/// value. This includes recognizing that %t0 and %t1 will have the same
-/// value in code like this:
-/// %t0 = getelementptr \@a, 0, 3
-/// store i32 0, i32* %t0
-/// %t1 = getelementptr \@a, 0, 3
-/// %t2 = load i32* %t1
-///
-static bool equivalentAddressValues(Value *A, Value *B) {
- // Test if the values are trivially equivalent.
- if (A == B) return true;
-
- // Test if the values come form identical arithmetic instructions.
- // This uses isIdenticalToWhenDefined instead of isIdenticalTo because
- // its only used to compare two uses within the same basic block, which
- // means that they'll always either have the same value or one of them
- // will have an undefined value.
- if (isa<BinaryOperator>(A) ||
- isa<CastInst>(A) ||
- isa<PHINode>(A) ||
- isa<GetElementPtrInst>(A))
- if (Instruction *BI = dyn_cast<Instruction>(B))
- if (cast<Instruction>(A)->isIdenticalToWhenDefined(BI))
- return true;
-
- // Otherwise they may not be equivalent.
- return false;
-}
-
-// If this instruction has two uses, one of which is a llvm.dbg.declare,
-// return the llvm.dbg.declare.
-DbgDeclareInst *InstCombiner::hasOneUsePlusDeclare(Value *V) {
- if (!V->hasNUses(2))
- return 0;
- for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
- UI != E; ++UI) {
- if (DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(UI))
- return DI;
- if (isa<BitCastInst>(UI) && UI->hasOneUse()) {
- if (DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(UI->use_begin()))
- return DI;
- }
- }
- return 0;
-}
-
-Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
- Value *Val = SI.getOperand(0);
- Value *Ptr = SI.getOperand(1);
-
- // If the RHS is an alloca with a single use, zapify the store, making the
- // alloca dead.
- // If the RHS is an alloca with a two uses, the other one being a
- // llvm.dbg.declare, zapify the store and the declare, making the
- // alloca dead. We must do this to prevent declare's from affecting
- // codegen.
- if (!SI.isVolatile()) {
- if (Ptr->hasOneUse()) {
- if (isa<AllocaInst>(Ptr)) {
- EraseInstFromFunction(SI);
- ++NumCombined;
- return 0;
- }
- if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
- if (isa<AllocaInst>(GEP->getOperand(0))) {
- if (GEP->getOperand(0)->hasOneUse()) {
- EraseInstFromFunction(SI);
- ++NumCombined;
- return 0;
- }
- if (DbgDeclareInst *DI = hasOneUsePlusDeclare(GEP->getOperand(0))) {
- EraseInstFromFunction(*DI);
- EraseInstFromFunction(SI);
- ++NumCombined;
- return 0;
- }
- }
- }
- }
- if (DbgDeclareInst *DI = hasOneUsePlusDeclare(Ptr)) {
- EraseInstFromFunction(*DI);
- EraseInstFromFunction(SI);
- ++NumCombined;
- return 0;
- }
- }
-
- // Attempt to improve the alignment.
- if (TD) {
- unsigned KnownAlign =
- GetOrEnforceKnownAlignment(Ptr, TD->getPrefTypeAlignment(Val->getType()));
- if (KnownAlign >
- (SI.getAlignment() == 0 ? TD->getABITypeAlignment(Val->getType()) :
- SI.getAlignment()))
- SI.setAlignment(KnownAlign);
- }
-
- // Do really simple DSE, to catch cases where there are several consecutive
- // stores to the same location, separated by a few arithmetic operations. This
- // situation often occurs with bitfield accesses.
- BasicBlock::iterator BBI = &SI;
- for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
- --ScanInsts) {
- --BBI;
- // Don't count debug info directives, lest they affect codegen,
- // and we skip pointer-to-pointer bitcasts, which are NOPs.
- // It is necessary for correctness to skip those that feed into a
- // llvm.dbg.declare, as these are not present when debugging is off.
- if (isa<DbgInfoIntrinsic>(BBI) ||
- (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType()))) {
- ScanInsts++;
- continue;
- }
-
- if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
- // Prev store isn't volatile, and stores to the same location?
- if (!PrevSI->isVolatile() &&equivalentAddressValues(PrevSI->getOperand(1),
- SI.getOperand(1))) {
- ++NumDeadStore;
- ++BBI;
- EraseInstFromFunction(*PrevSI);
- continue;
- }
- break;
- }
-
- // If this is a load, we have to stop. However, if the loaded value is from
- // the pointer we're loading and is producing the pointer we're storing,
- // then *this* store is dead (X = load P; store X -> P).
- if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
- if (LI == Val && equivalentAddressValues(LI->getOperand(0), Ptr) &&
- !SI.isVolatile()) {
- EraseInstFromFunction(SI);
- ++NumCombined;
- return 0;
- }
- // Otherwise, this is a load from some other location. Stores before it
- // may not be dead.
- break;
- }
-
- // Don't skip over loads or things that can modify memory.
- if (BBI->mayWriteToMemory() || BBI->mayReadFromMemory())
- break;
- }
-
-
- if (SI.isVolatile()) return 0; // Don't hack volatile stores.
-
- // store X, null -> turns into 'unreachable' in SimplifyCFG
- if (isa<ConstantPointerNull>(Ptr) && SI.getPointerAddressSpace() == 0) {
- if (!isa<UndefValue>(Val)) {
- SI.setOperand(0, UndefValue::get(Val->getType()));
- if (Instruction *U = dyn_cast<Instruction>(Val))
- Worklist.Add(U); // Dropped a use.
- ++NumCombined;
- }
- return 0; // Do not modify these!
- }
-
- // store undef, Ptr -> noop
- if (isa<UndefValue>(Val)) {
- EraseInstFromFunction(SI);
- ++NumCombined;
- return 0;
- }
-
- // If the pointer destination is a cast, see if we can fold the cast into the
- // source instead.
- if (isa<CastInst>(Ptr))
- if (Instruction *Res = InstCombineStoreToCast(*this, SI))
- return Res;
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
- if (CE->isCast())
- if (Instruction *Res = InstCombineStoreToCast(*this, SI))
- return Res;
-
-
- // If this store is the last instruction in the basic block (possibly
- // excepting debug info instructions and the pointer bitcasts that feed
- // into them), and if the block ends with an unconditional branch, try
- // to move it to the successor block.
- BBI = &SI;
- do {
- ++BBI;
- } while (isa<DbgInfoIntrinsic>(BBI) ||
- (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType())));
- if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
- if (BI->isUnconditional())
- if (SimplifyStoreAtEndOfBlock(SI))
- return 0; // xform done!
-
- return 0;
-}
-
-/// SimplifyStoreAtEndOfBlock - Turn things like:
-/// if () { *P = v1; } else { *P = v2 }
-/// into a phi node with a store in the successor.
-///
-/// Simplify things like:
-/// *P = v1; if () { *P = v2; }
-/// into a phi node with a store in the successor.
-///
-bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
- BasicBlock *StoreBB = SI.getParent();
-
- // Check to see if the successor block has exactly two incoming edges. If
- // so, see if the other predecessor contains a store to the same location.
- // if so, insert a PHI node (if needed) and move the stores down.
- BasicBlock *DestBB = StoreBB->getTerminator()->getSuccessor(0);
-
- // Determine whether Dest has exactly two predecessors and, if so, compute
- // the other predecessor.
- pred_iterator PI = pred_begin(DestBB);
- BasicBlock *OtherBB = 0;
- if (*PI != StoreBB)
- OtherBB = *PI;
- ++PI;
- if (PI == pred_end(DestBB))
- return false;
-
- if (*PI != StoreBB) {
- if (OtherBB)
- return false;
- OtherBB = *PI;
- }
- if (++PI != pred_end(DestBB))
- return false;
-
- // Bail out if all the relevant blocks aren't distinct (this can happen,
- // for example, if SI is in an infinite loop)
- if (StoreBB == DestBB || OtherBB == DestBB)
- return false;
-
- // Verify that the other block ends in a branch and is not otherwise empty.
- BasicBlock::iterator BBI = OtherBB->getTerminator();
- BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
- if (!OtherBr || BBI == OtherBB->begin())
- return false;
-
- // If the other block ends in an unconditional branch, check for the 'if then
- // else' case. there is an instruction before the branch.
- StoreInst *OtherStore = 0;
- if (OtherBr->isUnconditional()) {
- --BBI;
- // Skip over debugging info.
- while (isa<DbgInfoIntrinsic>(BBI) ||
- (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType()))) {
- if (BBI==OtherBB->begin())
- return false;
- --BBI;
- }
- // If this isn't a store, isn't a store to the same location, or if the
- // alignments differ, bail out.
- OtherStore = dyn_cast<StoreInst>(BBI);
- if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1) ||
- OtherStore->getAlignment() != SI.getAlignment())
- return false;
- } else {
- // Otherwise, the other block ended with a conditional branch. If one of the
- // destinations is StoreBB, then we have the if/then case.
- if (OtherBr->getSuccessor(0) != StoreBB &&
- OtherBr->getSuccessor(1) != StoreBB)
- return false;
-
- // Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an
- // if/then triangle. See if there is a store to the same ptr as SI that
- // lives in OtherBB.
- for (;; --BBI) {
- // Check to see if we find the matching store.
- if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
- if (OtherStore->getOperand(1) != SI.getOperand(1) ||
- OtherStore->getAlignment() != SI.getAlignment())
- return false;
- break;
- }
- // If we find something that may be using or overwriting the stored
- // value, or if we run out of instructions, we can't do the xform.
- if (BBI->mayReadFromMemory() || BBI->mayWriteToMemory() ||
- BBI == OtherBB->begin())
- return false;
- }
-
- // In order to eliminate the store in OtherBr, we have to
- // make sure nothing reads or overwrites the stored value in
- // StoreBB.
- for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) {
- // FIXME: This should really be AA driven.
- if (I->mayReadFromMemory() || I->mayWriteToMemory())
- return false;
- }
- }
-
- // Insert a PHI node now if we need it.
- Value *MergedVal = OtherStore->getOperand(0);
- if (MergedVal != SI.getOperand(0)) {
- PHINode *PN = PHINode::Create(MergedVal->getType(), "storemerge");
- PN->reserveOperandSpace(2);
- PN->addIncoming(SI.getOperand(0), SI.getParent());
- PN->addIncoming(OtherStore->getOperand(0), OtherBB);
- MergedVal = InsertNewInstBefore(PN, DestBB->front());
- }
-
- // Advance to a place where it is safe to insert the new store and
- // insert it.
- BBI = DestBB->getFirstNonPHI();
- InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
- OtherStore->isVolatile(),
- SI.getAlignment()), *BBI);
-
- // Nuke the old stores.
- EraseInstFromFunction(SI);
- EraseInstFromFunction(*OtherStore);
- ++NumCombined;
- return true;
-}
-
-
-Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
- // Change br (not X), label True, label False to: br X, label False, True
- Value *X = 0;
- BasicBlock *TrueDest;
- BasicBlock *FalseDest;
- if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
- !isa<Constant>(X)) {
- // Swap Destinations and condition...
- BI.setCondition(X);
- BI.setSuccessor(0, FalseDest);
- BI.setSuccessor(1, TrueDest);
- return &BI;
- }
-
- // Cannonicalize fcmp_one -> fcmp_oeq
- FCmpInst::Predicate FPred; Value *Y;
- if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)),
- TrueDest, FalseDest)) &&
- BI.getCondition()->hasOneUse())
- if (FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE ||
- FPred == FCmpInst::FCMP_OGE) {
- FCmpInst *Cond = cast<FCmpInst>(BI.getCondition());
- Cond->setPredicate(FCmpInst::getInversePredicate(FPred));
-
- // Swap Destinations and condition.
- BI.setSuccessor(0, FalseDest);
- BI.setSuccessor(1, TrueDest);
- Worklist.Add(Cond);
- return &BI;
- }
-
- // Cannonicalize icmp_ne -> icmp_eq
- ICmpInst::Predicate IPred;
- if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
- TrueDest, FalseDest)) &&
- BI.getCondition()->hasOneUse())
- if (IPred == ICmpInst::ICMP_NE || IPred == ICmpInst::ICMP_ULE ||
- IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE ||
- IPred == ICmpInst::ICMP_SGE) {
- ICmpInst *Cond = cast<ICmpInst>(BI.getCondition());
- Cond->setPredicate(ICmpInst::getInversePredicate(IPred));
- // Swap Destinations and condition.
- BI.setSuccessor(0, FalseDest);
- BI.setSuccessor(1, TrueDest);
- Worklist.Add(Cond);
- return &BI;
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
- Value *Cond = SI.getCondition();
- if (Instruction *I = dyn_cast<Instruction>(Cond)) {
- if (I->getOpcode() == Instruction::Add)
- if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
- // change 'switch (X+4) case 1:' into 'switch (X) case -3'
- for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
- SI.setOperand(i,
- ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
- AddRHS));
- SI.setOperand(0, I->getOperand(0));
- Worklist.Add(I);
- return &SI;
- }
- }
- return 0;
-}
-
-Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) {
- Value *Agg = EV.getAggregateOperand();
-
- if (!EV.hasIndices())
- return ReplaceInstUsesWith(EV, Agg);
-
- if (Constant *C = dyn_cast<Constant>(Agg)) {
- if (isa<UndefValue>(C))
- return ReplaceInstUsesWith(EV, UndefValue::get(EV.getType()));
-
- if (isa<ConstantAggregateZero>(C))
- return ReplaceInstUsesWith(EV, Constant::getNullValue(EV.getType()));
-
- if (isa<ConstantArray>(C) || isa<ConstantStruct>(C)) {
- // Extract the element indexed by the first index out of the constant
- Value *V = C->getOperand(*EV.idx_begin());
- if (EV.getNumIndices() > 1)
- // Extract the remaining indices out of the constant indexed by the
- // first index
- return ExtractValueInst::Create(V, EV.idx_begin() + 1, EV.idx_end());
- else
- return ReplaceInstUsesWith(EV, V);
- }
- return 0; // Can't handle other constants
- }
- if (InsertValueInst *IV = dyn_cast<InsertValueInst>(Agg)) {
- // We're extracting from an insertvalue instruction, compare the indices
- const unsigned *exti, *exte, *insi, *inse;
- for (exti = EV.idx_begin(), insi = IV->idx_begin(),
- exte = EV.idx_end(), inse = IV->idx_end();
- exti != exte && insi != inse;
- ++exti, ++insi) {
- if (*insi != *exti)
- // The insert and extract both reference distinctly different elements.
- // This means the extract is not influenced by the insert, and we can
- // replace the aggregate operand of the extract with the aggregate
- // operand of the insert. i.e., replace
- // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
- // %E = extractvalue { i32, { i32 } } %I, 0
- // with
- // %E = extractvalue { i32, { i32 } } %A, 0
- return ExtractValueInst::Create(IV->getAggregateOperand(),
- EV.idx_begin(), EV.idx_end());
- }
- if (exti == exte && insi == inse)
- // Both iterators are at the end: Index lists are identical. Replace
- // %B = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
- // %C = extractvalue { i32, { i32 } } %B, 1, 0
- // with "i32 42"
- return ReplaceInstUsesWith(EV, IV->getInsertedValueOperand());
- if (exti == exte) {
- // The extract list is a prefix of the insert list. i.e. replace
- // %I = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
- // %E = extractvalue { i32, { i32 } } %I, 1
- // with
- // %X = extractvalue { i32, { i32 } } %A, 1
- // %E = insertvalue { i32 } %X, i32 42, 0
- // by switching the order of the insert and extract (though the
- // insertvalue should be left in, since it may have other uses).
- Value *NewEV = Builder->CreateExtractValue(IV->getAggregateOperand(),
- EV.idx_begin(), EV.idx_end());
- return InsertValueInst::Create(NewEV, IV->getInsertedValueOperand(),
- insi, inse);
- }
- if (insi == inse)
- // The insert list is a prefix of the extract list
- // We can simply remove the common indices from the extract and make it
- // operate on the inserted value instead of the insertvalue result.
- // i.e., replace
- // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
- // %E = extractvalue { i32, { i32 } } %I, 1, 0
- // with
- // %E extractvalue { i32 } { i32 42 }, 0
- return ExtractValueInst::Create(IV->getInsertedValueOperand(),
- exti, exte);
- }
- if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Agg)) {
- // We're extracting from an intrinsic, see if we're the only user, which
- // allows us to simplify multiple result intrinsics to simpler things that
- // just get one value..
- if (II->hasOneUse()) {
- // Check if we're grabbing the overflow bit or the result of a 'with
- // overflow' intrinsic. If it's the latter we can remove the intrinsic
- // and replace it with a traditional binary instruction.
- switch (II->getIntrinsicID()) {
- case Intrinsic::uadd_with_overflow:
- case Intrinsic::sadd_with_overflow:
- if (*EV.idx_begin() == 0) { // Normal result.
- Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
- II->replaceAllUsesWith(UndefValue::get(II->getType()));
- EraseInstFromFunction(*II);
- return BinaryOperator::CreateAdd(LHS, RHS);
- }
- break;
- case Intrinsic::usub_with_overflow:
- case Intrinsic::ssub_with_overflow:
- if (*EV.idx_begin() == 0) { // Normal result.
- Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
- II->replaceAllUsesWith(UndefValue::get(II->getType()));
- EraseInstFromFunction(*II);
- return BinaryOperator::CreateSub(LHS, RHS);
- }
- break;
- case Intrinsic::umul_with_overflow:
- case Intrinsic::smul_with_overflow:
- if (*EV.idx_begin() == 0) { // Normal result.
- Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
- II->replaceAllUsesWith(UndefValue::get(II->getType()));
- EraseInstFromFunction(*II);
- return BinaryOperator::CreateMul(LHS, RHS);
- }
- break;
- default:
- break;
- }
- }
- }
- // Can't simplify extracts from other values. Note that nested extracts are
- // already simplified implicitely by the above (extract ( extract (insert) )
- // will be translated into extract ( insert ( extract ) ) first and then just
- // the value inserted, if appropriate).
- return 0;
-}
-
-/// CheapToScalarize - Return true if the value is cheaper to scalarize than it
-/// is to leave as a vector operation.
-static bool CheapToScalarize(Value *V, bool isConstant) {
- if (isa<ConstantAggregateZero>(V))
- return true;
- if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
- if (isConstant) return true;
- // If all elts are the same, we can extract.
- Constant *Op0 = C->getOperand(0);
- for (unsigned i = 1; i < C->getNumOperands(); ++i)
- if (C->getOperand(i) != Op0)
- return false;
- return true;
- }
- Instruction *I = dyn_cast<Instruction>(V);
- if (!I) return false;
-
- // Insert element gets simplified to the inserted element or is deleted if
- // this is constant idx extract element and its a constant idx insertelt.
- if (I->getOpcode() == Instruction::InsertElement && isConstant &&
- isa<ConstantInt>(I->getOperand(2)))
- return true;
- if (I->getOpcode() == Instruction::Load && I->hasOneUse())
- return true;
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
- if (BO->hasOneUse() &&
- (CheapToScalarize(BO->getOperand(0), isConstant) ||
- CheapToScalarize(BO->getOperand(1), isConstant)))
- return true;
- if (CmpInst *CI = dyn_cast<CmpInst>(I))
- if (CI->hasOneUse() &&
- (CheapToScalarize(CI->getOperand(0), isConstant) ||
- CheapToScalarize(CI->getOperand(1), isConstant)))
- return true;
-
- return false;
-}
-
-/// Read and decode a shufflevector mask.
-///
-/// It turns undef elements into values that are larger than the number of
-/// elements in the input.
-static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) {
- unsigned NElts = SVI->getType()->getNumElements();
- if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
- return std::vector<unsigned>(NElts, 0);
- if (isa<UndefValue>(SVI->getOperand(2)))
- return std::vector<unsigned>(NElts, 2*NElts);
-
- std::vector<unsigned> Result;
- const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
- for (User::const_op_iterator i = CP->op_begin(), e = CP->op_end(); i!=e; ++i)
- if (isa<UndefValue>(*i))
- Result.push_back(NElts*2); // undef -> 8
- else
- Result.push_back(cast<ConstantInt>(*i)->getZExtValue());
- return Result;
-}
-
-/// FindScalarElement - Given a vector and an element number, see if the scalar
-/// value is already around as a register, for example if it were inserted then
-/// extracted from the vector.
-static Value *FindScalarElement(Value *V, unsigned EltNo,
- LLVMContext *Context) {
- assert(isa<VectorType>(V->getType()) && "Not looking at a vector?");
- const VectorType *PTy = cast<VectorType>(V->getType());
- unsigned Width = PTy->getNumElements();
- if (EltNo >= Width) // Out of range access.
- return UndefValue::get(PTy->getElementType());
-
- if (isa<UndefValue>(V))
- return UndefValue::get(PTy->getElementType());
- else if (isa<ConstantAggregateZero>(V))
- return Constant::getNullValue(PTy->getElementType());
- else if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
- return CP->getOperand(EltNo);
- else if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
- // If this is an insert to a variable element, we don't know what it is.
- if (!isa<ConstantInt>(III->getOperand(2)))
- return 0;
- unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
-
- // If this is an insert to the element we are looking for, return the
- // inserted value.
- if (EltNo == IIElt)
- return III->getOperand(1);
-
- // Otherwise, the insertelement doesn't modify the value, recurse on its
- // vector input.
- return FindScalarElement(III->getOperand(0), EltNo, Context);
- } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
- unsigned LHSWidth =
- cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
- unsigned InEl = getShuffleMask(SVI)[EltNo];
- if (InEl < LHSWidth)
- return FindScalarElement(SVI->getOperand(0), InEl, Context);
- else if (InEl < LHSWidth*2)
- return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth, Context);
- else
- return UndefValue::get(PTy->getElementType());
- }
-
- // Otherwise, we don't know.
- return 0;
-}
-
-Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
- // If vector val is undef, replace extract with scalar undef.
- if (isa<UndefValue>(EI.getOperand(0)))
- return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
-
- // If vector val is constant 0, replace extract with scalar 0.
- if (isa<ConstantAggregateZero>(EI.getOperand(0)))
- return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
-
- if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
- // If vector val is constant with all elements the same, replace EI with
- // that element. When the elements are not identical, we cannot replace yet
- // (we do that below, but only when the index is constant).
- Constant *op0 = C->getOperand(0);
- for (unsigned i = 1; i != C->getNumOperands(); ++i)
- if (C->getOperand(i) != op0) {
- op0 = 0;
- break;
- }
- if (op0)
- return ReplaceInstUsesWith(EI, op0);
- }
-
- // If extracting a specified index from the vector, see if we can recursively
- // find a previously computed scalar that was inserted into the vector.
- if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
- unsigned IndexVal = IdxC->getZExtValue();
- unsigned VectorWidth = EI.getVectorOperandType()->getNumElements();
-
- // If this is extracting an invalid index, turn this into undef, to avoid
- // crashing the code below.
- if (IndexVal >= VectorWidth)
- return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
-
- // This instruction only demands the single element from the input vector.
- // If the input vector has a single use, simplify it based on this use
- // property.
- if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
- APInt UndefElts(VectorWidth, 0);
- APInt DemandedMask(VectorWidth, 1 << IndexVal);
- if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
- DemandedMask, UndefElts)) {
- EI.setOperand(0, V);
- return &EI;
- }
- }
-
- if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal, Context))
- return ReplaceInstUsesWith(EI, Elt);
-
- // If the this extractelement is directly using a bitcast from a vector of
- // the same number of elements, see if we can find the source element from
- // it. In this case, we will end up needing to bitcast the scalars.
- if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
- if (const VectorType *VT =
- dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
- if (VT->getNumElements() == VectorWidth)
- if (Value *Elt = FindScalarElement(BCI->getOperand(0),
- IndexVal, Context))
- return new BitCastInst(Elt, EI.getType());
- }
- }
-
- if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
- // Push extractelement into predecessor operation if legal and
- // profitable to do so
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
- if (I->hasOneUse() &&
- CheapToScalarize(BO, isa<ConstantInt>(EI.getOperand(1)))) {
- Value *newEI0 =
- Builder->CreateExtractElement(BO->getOperand(0), EI.getOperand(1),
- EI.getName()+".lhs");
- Value *newEI1 =
- Builder->CreateExtractElement(BO->getOperand(1), EI.getOperand(1),
- EI.getName()+".rhs");
- return BinaryOperator::Create(BO->getOpcode(), newEI0, newEI1);
- }
- } else if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
- // Extracting the inserted element?
- if (IE->getOperand(2) == EI.getOperand(1))
- return ReplaceInstUsesWith(EI, IE->getOperand(1));
- // If the inserted and extracted elements are constants, they must not
- // be the same value, extract from the pre-inserted value instead.
- if (isa<Constant>(IE->getOperand(2)) && isa<Constant>(EI.getOperand(1))) {
- Worklist.AddValue(EI.getOperand(0));
- EI.setOperand(0, IE->getOperand(0));
- return &EI;
- }
- } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) {
- // If this is extracting an element from a shufflevector, figure out where
- // it came from and extract from the appropriate input element instead.
- if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
- unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
- Value *Src;
- unsigned LHSWidth =
- cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
-
- if (SrcIdx < LHSWidth)
- Src = SVI->getOperand(0);
- else if (SrcIdx < LHSWidth*2) {
- SrcIdx -= LHSWidth;
- Src = SVI->getOperand(1);
- } else {
- return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
- }
- return ExtractElementInst::Create(Src,
- ConstantInt::get(Type::getInt32Ty(*Context), SrcIdx,
- false));
- }
- }
- // FIXME: Canonicalize extractelement(bitcast) -> bitcast(extractelement)
- }
- return 0;
-}
-
-/// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
-/// elements from either LHS or RHS, return the shuffle mask and true.
-/// Otherwise, return false.
-static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
- std::vector<Constant*> &Mask,
- LLVMContext *Context) {
- assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
- "Invalid CollectSingleShuffleElements");
- unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
-
- if (isa<UndefValue>(V)) {
- Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(*Context)));
- return true;
- } else if (V == LHS) {
- for (unsigned i = 0; i != NumElts; ++i)
- Mask.push_back(ConstantInt::get(Type::getInt32Ty(*Context), i));
- return true;
- } else if (V == RHS) {
- for (unsigned i = 0; i != NumElts; ++i)
- Mask.push_back(ConstantInt::get(Type::getInt32Ty(*Context), i+NumElts));
- return true;
- } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
- // If this is an insert of an extract from some other vector, include it.
- Value *VecOp = IEI->getOperand(0);
- Value *ScalarOp = IEI->getOperand(1);
- Value *IdxOp = IEI->getOperand(2);
-
- if (!isa<ConstantInt>(IdxOp))
- return false;
- unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
-
- if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
- // Okay, we can handle this if the vector we are insertinting into is
- // transitively ok.
- if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask, Context)) {
- // If so, update the mask to reflect the inserted undef.
- Mask[InsertedIdx] = UndefValue::get(Type::getInt32Ty(*Context));
- return true;
- }
- } else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
- if (isa<ConstantInt>(EI->getOperand(1)) &&
- EI->getOperand(0)->getType() == V->getType()) {
- unsigned ExtractedIdx =
- cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
-
- // This must be extracting from either LHS or RHS.
- if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
- // Okay, we can handle this if the vector we are insertinting into is
- // transitively ok.
- if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask, Context)) {
- // If so, update the mask to reflect the inserted value.
- if (EI->getOperand(0) == LHS) {
- Mask[InsertedIdx % NumElts] =
- ConstantInt::get(Type::getInt32Ty(*Context), ExtractedIdx);
- } else {
- assert(EI->getOperand(0) == RHS);
- Mask[InsertedIdx % NumElts] =
- ConstantInt::get(Type::getInt32Ty(*Context), ExtractedIdx+NumElts);
-
- }
- return true;
- }
- }
- }
- }
- }
- // TODO: Handle shufflevector here!
-
- return false;
-}
-
-/// CollectShuffleElements - We are building a shuffle of V, using RHS as the
-/// RHS of the shuffle instruction, if it is not null. Return a shuffle mask
-/// that computes V and the LHS value of the shuffle.
-static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
- Value *&RHS, LLVMContext *Context) {
- assert(isa<VectorType>(V->getType()) &&
- (RHS == 0 || V->getType() == RHS->getType()) &&
- "Invalid shuffle!");
- unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
-
- if (isa<UndefValue>(V)) {
- Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(*Context)));
- return V;
- } else if (isa<ConstantAggregateZero>(V)) {
- Mask.assign(NumElts, ConstantInt::get(Type::getInt32Ty(*Context), 0));
- return V;
- } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
- // If this is an insert of an extract from some other vector, include it.
- Value *VecOp = IEI->getOperand(0);
- Value *ScalarOp = IEI->getOperand(1);
- Value *IdxOp = IEI->getOperand(2);
-
- if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
- if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
- EI->getOperand(0)->getType() == V->getType()) {
- unsigned ExtractedIdx =
- cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
- unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
-
- // Either the extracted from or inserted into vector must be RHSVec,
- // otherwise we'd end up with a shuffle of three inputs.
- if (EI->getOperand(0) == RHS || RHS == 0) {
- RHS = EI->getOperand(0);
- Value *V = CollectShuffleElements(VecOp, Mask, RHS, Context);
- Mask[InsertedIdx % NumElts] =
- ConstantInt::get(Type::getInt32Ty(*Context), NumElts+ExtractedIdx);
- return V;
- }
-
- if (VecOp == RHS) {
- Value *V = CollectShuffleElements(EI->getOperand(0), Mask,
- RHS, Context);
- // Everything but the extracted element is replaced with the RHS.
- for (unsigned i = 0; i != NumElts; ++i) {
- if (i != InsertedIdx)
- Mask[i] = ConstantInt::get(Type::getInt32Ty(*Context), NumElts+i);
- }
- return V;
- }
-
- // If this insertelement is a chain that comes from exactly these two
- // vectors, return the vector and the effective shuffle.
- if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask,
- Context))
- return EI->getOperand(0);
-
- }
- }
- }
- // TODO: Handle shufflevector here!
-
- // Otherwise, can't do anything fancy. Return an identity vector.
- for (unsigned i = 0; i != NumElts; ++i)
- Mask.push_back(ConstantInt::get(Type::getInt32Ty(*Context), i));
- return V;
-}
-
-Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
- Value *VecOp = IE.getOperand(0);
- Value *ScalarOp = IE.getOperand(1);
- Value *IdxOp = IE.getOperand(2);
-
- // Inserting an undef or into an undefined place, remove this.
- if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
- ReplaceInstUsesWith(IE, VecOp);
-
- // If the inserted element was extracted from some other vector, and if the
- // indexes are constant, try to turn this into a shufflevector operation.
- if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
- if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
- EI->getOperand(0)->getType() == IE.getType()) {
- unsigned NumVectorElts = IE.getType()->getNumElements();
- unsigned ExtractedIdx =
- cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
- unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
-
- if (ExtractedIdx >= NumVectorElts) // Out of range extract.
- return ReplaceInstUsesWith(IE, VecOp);
-
- if (InsertedIdx >= NumVectorElts) // Out of range insert.
- return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
-
- // If we are extracting a value from a vector, then inserting it right
- // back into the same place, just use the input vector.
- if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
- return ReplaceInstUsesWith(IE, VecOp);
-
- // If this insertelement isn't used by some other insertelement, turn it
- // (and any insertelements it points to), into one big shuffle.
- if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
- std::vector<Constant*> Mask;
- Value *RHS = 0;
- Value *LHS = CollectShuffleElements(&IE, Mask, RHS, Context);
- if (RHS == 0) RHS = UndefValue::get(LHS->getType());
- // We now have a shuffle of LHS, RHS, Mask.
- return new ShuffleVectorInst(LHS, RHS,
- ConstantVector::get(Mask));
- }
- }
- }
-
- unsigned VWidth = cast<VectorType>(VecOp->getType())->getNumElements();
- APInt UndefElts(VWidth, 0);
- APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
- if (SimplifyDemandedVectorElts(&IE, AllOnesEltMask, UndefElts))
- return &IE;
-
- return 0;
-}
-
-
-Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
- Value *LHS = SVI.getOperand(0);
- Value *RHS = SVI.getOperand(1);
- std::vector<unsigned> Mask = getShuffleMask(&SVI);
-
- bool MadeChange = false;
-
- // Undefined shuffle mask -> undefined value.
- if (isa<UndefValue>(SVI.getOperand(2)))
- return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
-
- unsigned VWidth = cast<VectorType>(SVI.getType())->getNumElements();
-
- if (VWidth != cast<VectorType>(LHS->getType())->getNumElements())
- return 0;
-
- APInt UndefElts(VWidth, 0);
- APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
- if (SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
- LHS = SVI.getOperand(0);
- RHS = SVI.getOperand(1);
- MadeChange = true;
- }
-
- // Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
- // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
- if (LHS == RHS || isa<UndefValue>(LHS)) {
- if (isa<UndefValue>(LHS) && LHS == RHS) {
- // shuffle(undef,undef,mask) -> undef.
- return ReplaceInstUsesWith(SVI, LHS);
- }
-
- // Remap any references to RHS to use LHS.
- std::vector<Constant*> Elts;
- for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
- if (Mask[i] >= 2*e)
- Elts.push_back(UndefValue::get(Type::getInt32Ty(*Context)));
- else {
- if ((Mask[i] >= e && isa<UndefValue>(RHS)) ||
- (Mask[i] < e && isa<UndefValue>(LHS))) {
- Mask[i] = 2*e; // Turn into undef.
- Elts.push_back(UndefValue::get(Type::getInt32Ty(*Context)));
- } else {
- Mask[i] = Mask[i] % e; // Force to LHS.
- Elts.push_back(ConstantInt::get(Type::getInt32Ty(*Context), Mask[i]));
- }
- }
- }
- SVI.setOperand(0, SVI.getOperand(1));
- SVI.setOperand(1, UndefValue::get(RHS->getType()));
- SVI.setOperand(2, ConstantVector::get(Elts));
- LHS = SVI.getOperand(0);
- RHS = SVI.getOperand(1);
- MadeChange = true;
- }
-
- // Analyze the shuffle, are the LHS or RHS and identity shuffles?
- bool isLHSID = true, isRHSID = true;
-
- for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
- if (Mask[i] >= e*2) continue; // Ignore undef values.
- // Is this an identity shuffle of the LHS value?
- isLHSID &= (Mask[i] == i);
-
- // Is this an identity shuffle of the RHS value?
- isRHSID &= (Mask[i]-e == i);
- }
-
- // Eliminate identity shuffles.
- if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
- if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
-
- // If the LHS is a shufflevector itself, see if we can combine it with this
- // one without producing an unusual shuffle. Here we are really conservative:
- // we are absolutely afraid of producing a shuffle mask not in the input
- // program, because the code gen may not be smart enough to turn a merged
- // shuffle into two specific shuffles: it may produce worse code. As such,
- // we only merge two shuffles if the result is one of the two input shuffle
- // masks. In this case, merging the shuffles just removes one instruction,
- // which we know is safe. This is good for things like turning:
- // (splat(splat)) -> splat.
- if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
- if (isa<UndefValue>(RHS)) {
- std::vector<unsigned> LHSMask = getShuffleMask(LHSSVI);
-
- if (LHSMask.size() == Mask.size()) {
- std::vector<unsigned> NewMask;
- for (unsigned i = 0, e = Mask.size(); i != e; ++i)
- if (Mask[i] >= e)
- NewMask.push_back(2*e);
- else
- NewMask.push_back(LHSMask[Mask[i]]);
-
- // If the result mask is equal to the src shuffle or this
- // shuffle mask, do the replacement.
- if (NewMask == LHSMask || NewMask == Mask) {
- unsigned LHSInNElts =
- cast<VectorType>(LHSSVI->getOperand(0)->getType())->
- getNumElements();
- std::vector<Constant*> Elts;
- for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
- if (NewMask[i] >= LHSInNElts*2) {
- Elts.push_back(UndefValue::get(Type::getInt32Ty(*Context)));
- } else {
- Elts.push_back(ConstantInt::get(Type::getInt32Ty(*Context),
- NewMask[i]));
- }
- }
- return new ShuffleVectorInst(LHSSVI->getOperand(0),
- LHSSVI->getOperand(1),
- ConstantVector::get(Elts));
- }
- }
- }
- }
-
- return MadeChange ? &SVI : 0;
-}
-
-
-
-
-/// TryToSinkInstruction - Try to move the specified instruction from its
-/// current block into the beginning of DestBlock, which can only happen if it's
-/// safe to move the instruction past all of the instructions between it and the
-/// end of its block.
-static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
- assert(I->hasOneUse() && "Invariants didn't hold!");
-
- // Cannot move control-flow-involving, volatile loads, vaarg, etc.
- if (isa<PHINode>(I) || I->mayHaveSideEffects() || isa<TerminatorInst>(I))
- return false;
-
- // Do not sink alloca instructions out of the entry block.
- if (isa<AllocaInst>(I) && I->getParent() ==
- &DestBlock->getParent()->getEntryBlock())
- return false;
-
- // We can only sink load instructions if there is nothing between the load and
- // the end of block that could change the value.
- if (I->mayReadFromMemory()) {
- for (BasicBlock::iterator Scan = I, E = I->getParent()->end();
- Scan != E; ++Scan)
- if (Scan->mayWriteToMemory())
- return false;
- }
-
- BasicBlock::iterator InsertPos = DestBlock->getFirstNonPHI();
-
- CopyPrecedingStopPoint(I, InsertPos);
- I->moveBefore(InsertPos);
- ++NumSunkInst;
- return true;
-}
-
-
-/// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
-/// all reachable code to the worklist.
-///
-/// This has a couple of tricks to make the code faster and more powerful. In
-/// particular, we constant fold and DCE instructions as we go, to avoid adding
-/// them to the worklist (this significantly speeds up instcombine on code where
-/// many instructions are dead or constant). Additionally, if we find a branch
-/// whose condition is a known constant, we only visit the reachable successors.
-///
-static bool AddReachableCodeToWorklist(BasicBlock *BB,
- SmallPtrSet<BasicBlock*, 64> &Visited,
- InstCombiner &IC,
- const TargetData *TD) {
- bool MadeIRChange = false;
- SmallVector<BasicBlock*, 256> Worklist;
- Worklist.push_back(BB);
-
- std::vector<Instruction*> InstrsForInstCombineWorklist;
- InstrsForInstCombineWorklist.reserve(128);
-
- SmallPtrSet<ConstantExpr*, 64> FoldedConstants;
-
- while (!Worklist.empty()) {
- BB = Worklist.back();
- Worklist.pop_back();
-
- // We have now visited this block! If we've already been here, ignore it.
- if (!Visited.insert(BB)) continue;
-
- for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
- Instruction *Inst = BBI++;
-
- // DCE instruction if trivially dead.
- if (isInstructionTriviallyDead(Inst)) {
- ++NumDeadInst;
- DEBUG(errs() << "IC: DCE: " << *Inst << '\n');
- Inst->eraseFromParent();
- continue;
- }
-
- // ConstantProp instruction if trivially constant.
- if (!Inst->use_empty() && isa<Constant>(Inst->getOperand(0)))
- if (Constant *C = ConstantFoldInstruction(Inst, TD)) {
- DEBUG(errs() << "IC: ConstFold to: " << *C << " from: "
- << *Inst << '\n');
- Inst->replaceAllUsesWith(C);
- ++NumConstProp;
- Inst->eraseFromParent();
- continue;
- }
-
-
-
- if (TD) {
- // See if we can constant fold its operands.
- for (User::op_iterator i = Inst->op_begin(), e = Inst->op_end();
- i != e; ++i) {
- ConstantExpr *CE = dyn_cast<ConstantExpr>(i);
- if (CE == 0) continue;
-
- // If we already folded this constant, don't try again.
- if (!FoldedConstants.insert(CE))
- continue;
-
- Constant *NewC = ConstantFoldConstantExpression(CE, TD);
- if (NewC && NewC != CE) {
- *i = NewC;
- MadeIRChange = true;
- }
- }
- }
-
-
- InstrsForInstCombineWorklist.push_back(Inst);
- }
-
- // Recursively visit successors. If this is a branch or switch on a
- // constant, only visit the reachable successor.
- TerminatorInst *TI = BB->getTerminator();
- if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
- if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
- bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
- BasicBlock *ReachableBB = BI->getSuccessor(!CondVal);
- Worklist.push_back(ReachableBB);
- continue;
- }
- } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
- if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
- // See if this is an explicit destination.
- for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i)
- if (SI->getCaseValue(i) == Cond) {
- BasicBlock *ReachableBB = SI->getSuccessor(i);
- Worklist.push_back(ReachableBB);
- continue;
- }
-
- // Otherwise it is the default destination.
- Worklist.push_back(SI->getSuccessor(0));
- continue;
- }
- }
-
- for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
- Worklist.push_back(TI->getSuccessor(i));
- }
-
- // Once we've found all of the instructions to add to instcombine's worklist,
- // add them in reverse order. This way instcombine will visit from the top
- // of the function down. This jives well with the way that it adds all uses
- // of instructions to the worklist after doing a transformation, thus avoiding
- // some N^2 behavior in pathological cases.
- IC.Worklist.AddInitialGroup(&InstrsForInstCombineWorklist[0],
- InstrsForInstCombineWorklist.size());
-
- return MadeIRChange;
-}
-
-bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
- MadeIRChange = false;
-
- DEBUG(errs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
- << F.getNameStr() << "\n");
-
- {
- // Do a depth-first traversal of the function, populate the worklist with
- // the reachable instructions. Ignore blocks that are not reachable. Keep
- // track of which blocks we visit.
- SmallPtrSet<BasicBlock*, 64> Visited;
- MadeIRChange |= AddReachableCodeToWorklist(F.begin(), Visited, *this, TD);
-
- // Do a quick scan over the function. If we find any blocks that are
- // unreachable, remove any instructions inside of them. This prevents
- // the instcombine code from having to deal with some bad special cases.
- for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
- if (!Visited.count(BB)) {
- Instruction *Term = BB->getTerminator();
- while (Term != BB->begin()) { // Remove instrs bottom-up
- BasicBlock::iterator I = Term; --I;
-
- DEBUG(errs() << "IC: DCE: " << *I << '\n');
- // A debug intrinsic shouldn't force another iteration if we weren't
- // going to do one without it.
- if (!isa<DbgInfoIntrinsic>(I)) {
- ++NumDeadInst;
- MadeIRChange = true;
- }
-
- // If I is not void type then replaceAllUsesWith undef.
- // This allows ValueHandlers and custom metadata to adjust itself.
- if (!I->getType()->isVoidTy())
- I->replaceAllUsesWith(UndefValue::get(I->getType()));
- I->eraseFromParent();
- }
- }
- }
-
- while (!Worklist.isEmpty()) {
- Instruction *I = Worklist.RemoveOne();
- if (I == 0) continue; // skip null values.
-
- // Check to see if we can DCE the instruction.
- if (isInstructionTriviallyDead(I)) {
- DEBUG(errs() << "IC: DCE: " << *I << '\n');
- EraseInstFromFunction(*I);
- ++NumDeadInst;
- MadeIRChange = true;
- continue;
- }
-
- // Instruction isn't dead, see if we can constant propagate it.
- if (!I->use_empty() && isa<Constant>(I->getOperand(0)))
- if (Constant *C = ConstantFoldInstruction(I, TD)) {
- DEBUG(errs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
-
- // Add operands to the worklist.
- ReplaceInstUsesWith(*I, C);
- ++NumConstProp;
- EraseInstFromFunction(*I);
- MadeIRChange = true;
- continue;
- }
-
- // See if we can trivially sink this instruction to a successor basic block.
- if (I->hasOneUse()) {
- BasicBlock *BB = I->getParent();
- Instruction *UserInst = cast<Instruction>(I->use_back());
- BasicBlock *UserParent;
-
- // Get the block the use occurs in.
- if (PHINode *PN = dyn_cast<PHINode>(UserInst))
- UserParent = PN->getIncomingBlock(I->use_begin().getUse());
- else
- UserParent = UserInst->getParent();
-
- if (UserParent != BB) {
- bool UserIsSuccessor = false;
- // See if the user is one of our successors.
- for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
- if (*SI == UserParent) {
- UserIsSuccessor = true;
- break;
- }
-
- // If the user is one of our immediate successors, and if that successor
- // only has us as a predecessors (we'd have to split the critical edge
- // otherwise), we can keep going.
- if (UserIsSuccessor && UserParent->getSinglePredecessor())
- // Okay, the CFG is simple enough, try to sink this instruction.
- MadeIRChange |= TryToSinkInstruction(I, UserParent);
- }
- }
-
- // Now that we have an instruction, try combining it to simplify it.
- Builder->SetInsertPoint(I->getParent(), I);
-
-#ifndef NDEBUG
- std::string OrigI;
-#endif
- DEBUG(raw_string_ostream SS(OrigI); I->print(SS); OrigI = SS.str(););
- DEBUG(errs() << "IC: Visiting: " << OrigI << '\n');
-
- if (Instruction *Result = visit(*I)) {
- ++NumCombined;
- // Should we replace the old instruction with a new one?
- if (Result != I) {
- DEBUG(errs() << "IC: Old = " << *I << '\n'
- << " New = " << *Result << '\n');
-
- // Everything uses the new instruction now.
- I->replaceAllUsesWith(Result);
-
- // Push the new instruction and any users onto the worklist.
- Worklist.Add(Result);
- Worklist.AddUsersToWorkList(*Result);
-
- // Move the name to the new instruction first.
- Result->takeName(I);
-
- // Insert the new instruction into the basic block...
- BasicBlock *InstParent = I->getParent();
- BasicBlock::iterator InsertPos = I;
-
- if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
- while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
- ++InsertPos;
-
- InstParent->getInstList().insert(InsertPos, Result);
-
- EraseInstFromFunction(*I);
- } else {
-#ifndef NDEBUG
- DEBUG(errs() << "IC: Mod = " << OrigI << '\n'
- << " New = " << *I << '\n');
-#endif
-
- // If the instruction was modified, it's possible that it is now dead.
- // if so, remove it.
- if (isInstructionTriviallyDead(I)) {
- EraseInstFromFunction(*I);
- } else {
- Worklist.Add(I);
- Worklist.AddUsersToWorkList(*I);
- }
- }
- MadeIRChange = true;
- }
- }
-
- Worklist.Zap();
- return MadeIRChange;
-}
-
-
-bool InstCombiner::runOnFunction(Function &F) {
- MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
- Context = &F.getContext();
- TD = getAnalysisIfAvailable<TargetData>();
-
-
- /// Builder - This is an IRBuilder that automatically inserts new
- /// instructions into the worklist when they are created.
- IRBuilder<true, TargetFolder, InstCombineIRInserter>
- TheBuilder(F.getContext(), TargetFolder(TD),
- InstCombineIRInserter(Worklist));
- Builder = &TheBuilder;
-
- bool EverMadeChange = false;
-
- // Iterate while there is work to do.
- unsigned Iteration = 0;
- while (DoOneIteration(F, Iteration++))
- EverMadeChange = true;
-
- Builder = 0;
- return EverMadeChange;
-}
-
-FunctionPass *llvm::createInstructionCombiningPass() {
- return new InstCombiner();
-}
projects / oota-llvm.git / commitdiff